zvezde.1.bata.,
Da li neko kojim slucajem zna nesto vise o kometi koja bi trebalo da
se vidi golim okom (pod uslovom da je vedro) iz Beograda ovih dana ?
zvezde.2dvesic,
> Da li neko kojim slucajem zna nesto vise o kometi koja bi trebalo da
> se vidi golim okom (pod uslovom da je vedro) iz Beograda ovih dana ?
Prenosim poruku gorans-a sa Sezam Pro-a, nadam se da se nece ljutiti :))
================================
Razonoda, Zvezde.25, gorans
(10.25) Uto 12/03/1996 19:58, 6317 chr
----------------------------------------------------------------
Evo podataka o kometi HYAKUTAKE:
COMET C/1996 B2 (HYAKUTAKE)
The comet announced on E1041 has been re-designated as above.
Brian Marsden, Central Bureau has derived the following orbital
elements from 33 measures submitted to CBAT and obtained 1996
Jan 31-Feb 3:
T = 1996 May 2.769 TT Peri. = 131.202
Node = 188.943 2000.0
q = 0.22432 AU Incl. = 122.639
(IAUC 6303 extract)
Ephemeris by G.Hurst using EPH.EXE by Nick James:
m = 5.5 + 5.0 log R + 10.0 log r
Date R.A. (2000) Dec. R r Elong Mag. Motion
h m o ' (AU) (AU) o "/hr P.A.
1996 Feb
2.00 14 33.06 -24 56.3 1.788 2.022 88.7 9.8 27 91
3.00 14 33.85 -24 56.4 1.755 2.006 89.5 9.7 27 90
4.00 14 34.63 -24 56.3 1.722 1.990 90.3 9.7 27 89
5.00 14 35.41 -24 56.0 1.689 1.973 91.2 9.6 26 88
6.00 14 36.18 -24 55.5 1.656 1.957 92.0 9.5 26 87
7.00 14 36.94 -24 54.9 1.623 1.941 92.9 9.4 26 86
8.00 14 37.70 -24 53.9 1.590 1.924 93.7 9.3 26 84
9.00 14 38.44 -24 52.8 1.556 1.908 94.5 9.3 25 83
10.00 14 39.18 -24 51.4 1.523 1.891 95.4 9.2 25 81
11.00 14 39.91 -24 49.7 1.490 1.874 96.2 9.1 25 80
12.00 14 40.63 -24 47.7 1.456 1.858 97.1 9.0 25 78
13.00 14 41.34 -24 45.5 1.423 1.841 98.0 8.9 25 76
14.00 14 42.04 -24 42.9 1.390 1.824 98.8 8.8 25 74
15.00 14 42.73 -24 39.9 1.356 1.807 99.7 8.7 25 72
16.00 14 43.40 -24 36.6 1.323 1.790 100.6 8.6 25 69
17.00 14 44.07 -24 32.9 1.289 1.773 101.4 8.5 25 67
18.00 14 44.73 -24 28.7 1.256 1.756 102.3 8.4 25 64
19.00 14 45.37 -24 24.1 1.222 1.739 103.2 8.3 25 61
20.00 14 46.00 -24 18.9 1.189 1.722 104.1 8.2 25 58
21.00 14 46.61 -24 13.3 1.156 1.704 105.0 8.1 26 55
22.00 14 47.21 -24 7.0 1.122 1.687 105.9 8.0 26 51
23.00 14 47.80 -24 0.1 1.089 1.669 106.8 7.9 27 48
24.00 14 48.37 -23 52.5 1.055 1.652 107.7 7.8 28 44
25.00 14 48.92 -23 44.1 1.022 1.634 108.7 7.7 29 41
26.00 14 49.46 -23 34.9 0.988 1.617 109.6 7.6 30 37
27.00 14 49.98 -23 24.8 0.955 1.599 110.5 7.4 32 34
28.00 14 50.48 -23 13.6 0.922 1.581 111.5 7.3 34 30
29.00 14 50.96 -23 1.4 0.888 1.563 112.4 7.2 36 27
1996 Mar
1.00 14 51.43 -22 47.9 0.855 1.545 113.4 7.0 39 24
2.00 14 51.86 -22 33.0 0.822 1.527 114.4 6.9 42 21
3.00 14 52.28 -22 16.6 0.789 1.508 115.4 6.8 45 18
4.00 14 52.67 -21 58.4 0.755 1.490 116.4 6.6 49 16
5.00 14 53.04 -21 38.3 0.722 1.472 117.4 6.5 54 13
6.00 14 53.37 -21 15.9 0.689 1.453 118.5 6.3 60 11
7.00 14 53.68 -20 51.0 0.656 1.435 119.6 6.2 66 9
8.00 14 53.95 -20 23.1 0.623 1.416 120.6 6.0 74 7
9.00 14 54.18 -19 51.8 0.590 1.397 121.8 5.8 83 5
10.00 14 54.38 -19 16.4 0.558 1.378 122.9 5.6 94 4
11.00 14 54.52 -18 36.4 0.525 1.359 124.1 5.4 106 2
12.00 14 54.61 -17 50.7 0.493 1.340 125.3 5.2 121 1
13.00 14 54.65 -16 58.2 0.460 1.321 126.5 5.0 140 0
14.00 14 54.61 -15 57.5 0.428 1.301 127.8 4.8 162 359
15.00 14 54.49 -14 46.6 0.396 1.282 129.2 4.6 190 358
16.00 14 54.27 -13 23.0 0.364 1.262 130.6 4.3 226 358
17.00 14 53.94 -11 43.2 0.333 1.243 132.0 4.1 271 357
18.00 14 53.46 -9 42.5 0.302 1.223 133.5 3.8 331 356
19.00 14 52.79 -7 13.9 0.271 1.203 135.1 3.5 410 356
20.00 14 51.88 -4 7.9 0.241 1.183 136.6 3.1 518 356
21.00 14 50.63 -0 10.2 0.212 1.163 138.0 2.8 668 355
22.00 14 48.91 +5 0.5 0.185 1.142 139.0 2.4 882 355
23.00 14 46.46 +11 55.0 0.159 1.122 139.0 2.0 1185 355
24.00 14 42.83 +21 14.6 0.137 1.101 137.0 1.6 1602 355
25.00 14 37.05 +33 40.7 0.120 1.080 131.6 1.2 2103 354
26.00 14 26.64 +49 13.3 0.110 1.059 121.8 1.0 2516 352
27.00 14 2.94 +66 9.6 0.109 1.038 109.0 0.9 2563 348
28.00 12 28.32 +80 59.2 0.118 1.017 96.0 0.9 2171 328
29.00 5 44.40 +82 17.4 0.134 0.996 85.0 1.1 1761 228
30.00 4 5.86 +73 47.4 0.156 0.974 76.5 1.3 1275 200
31.00 3 41.52 +66 51.5 0.181 0.953 70.0 1.6 947 194
1996 Apr
1.00 3 30.75 +61 33.9 0.208 0.931 65.0 1.8 717 191
2.00 3 24.64 +57 28.7 0.236 0.909 60.9 1.9 556 190
3.00 3 20.65 +54 15.5 0.265 0.886 57.6 2.1 442 190
4.00 3 17.79 +51 39.9 0.295 0.864 54.7 2.2 359 189
5.00 3 15.58 +49 31.9 0.326 0.841 52.2 2.3 298 189
6.00 3 13.79 +47 44.8 0.356 0.819 50.0 2.4 252 190
7.00 3 12.26 +46 13.5 0.387 0.796 48.0 2.4 216 190
8.00 3 10.91 +44 54.4 0.419 0.772 46.1 2.5 189 190
9.00 3 9.67 +43 45.0 0.450 0.749 44.3 2.5 168 191
10.00 3 8.50 +42 43.1 0.482 0.725 42.7 2.5 151 192
As observers will note the comet has every prospect of becoming
a naked eye object during March as it makes a close approach to
the Earth.(1996 Mar 27, 0.11AU). In the latter part of March it is
also extremely well placed for observation from northern hemisphere
latitudes.
Whilst detailed plans are already being drawn up on a worldwide
basis for the study of Comet C/1995 O1 (Hale-Bopp), it now appears
the Comet C/1996 B2 could become an even brighter and better placed
object and both comets should present an excellent opportunity
for observers who should begin preparations as soon as possible.
The above ephemeris is highly uncertain, especially in late March
but should assist with planning observations.
------------------------------------------------------------------
Toliko za sad...
-------------------------------------------------10.25 --
I od mene :)
zvezde.3nothingman,
Zna li neko da li se u Bgdu ili u Srbiji mogu pronaci prodavnice koje
se bave prodajom Teleskopa i sl. stvari?
zvezde.4nenad,
> Zna li neko da li se u Bgdu ili u Srbiji mogu pronaci prodavnice koje
> se bave prodajom Teleskopa i sl. stvari?
Najbolje je da se raspitaš u Astronomskom društvu "Ruđer
Bošković" u Narodnoj opservatoriji na Kalemegdanu. Potraži
Milana Jeličića, reci slobodno da sam te ja uputio.
zvezde.5.bata.,
>> Zna li neko da li se u Bgdu ili u Srbiji mogu pronaci
>> prodavnice koje se bave prodajom Teleskopa i sl. stvari?
U Beogradu mozes kupiti teleskop samo ako nadjes nekog ko bi ti
prodao svoj polovan (naravno kupljen u inostranstvu) ili ako nagovoris
nekog da ti ga iz inostranstva donese.
> Najbolje je da se raspitas u Astronomskom drustvu "Ruder
> Boskovic" u Narodnoj opservatoriji na Kalemegdanu. Potrazi
Bojim se da su oni van svih svetskih tokova i da ce te belo pogledati.
> Potrazi
> Milana Jelicica, reci slobodno da sam te ja uputio.
Do Mice se lako dolazi i bez ikakve preporuke, ali na zalost od njega
mozezs saznati samo najnovije traceve o kalemegdanskim homoseksualcima ;(
Oni su ti od slabe pomoci... :( Ako bi bas da probas i kod njih evo ti
br. tel. 624605. - najbolje je zvati petkom i subotom popodne (od 16-22)
Pokusaj da odes na zvezdaru (pod glupim nazivom Astronomska opservatorija)
i uz malo srece (to znaci ako zateknes nekog normalnog i budes dovoljno
uporan) mozda ti podje za rukom da do nekog izvora i dodjes.
Pokusaj da se javis na br. tel. 401320 i mozes traziti bilo koga od osoblja
(izbegni bibliotekarke :) ) ako uspes da uhvatis probaj da davis
Luku Ch. Popovica, Dimitrijevica, ... ima puno entuzijasta.
zvezde.6nenad,
> U Beogradu mozes kupiti teleskop samo ako nadjes nekog ko bi ti
> prodao svoj polovan (naravno kupljen u inostranstvu) ili ako nagovoris
> nekog da ti ga iz inostranstva donese.
... ili ako ga sam napraviš... ako znaš. :)
> Bojim se da su oni van svih svetskih tokova i da ce te belo pogledati.
Za informacije o pravljenju i nabavci teleskopa nije potrebno
biti u svetskim tokovima. Tu se ništa značajno nije promenilo
poslednjih 50 godina, naročito ne u klasi aparata koji tebe
zanimaju.
> Luku Ch. Popovica, Dimitrijevica, ... ima puno entuzijasta.
Isti ljudi se mogu pronaći i na Narodnoj opservatoriji. Nju sam
preporučio jer je lakše do nje doći, spremniji su da ti pomognu,
daju neku adresu na koju možeš da se obratiš. Tačno je da se do
Miće Jeličića može doći i bez "preporuke", ali ona ume da
pomogne. :)
zvezde.7.bata.,
>... ili ako ga sam napravis... ako znas. :)
Sve jedno je. Ondaaa morres socivaaaa ili ogledala da nabavljas
(togaa kod nas opet nema), a i ako te je malo vise zanimala optika
verovatno znas da su sistemi za korkciju svih mogucih aberacija veoma
komplikovani...
>poslednjih 50 godina, narocito ne u klasi aparata koji tebe
>zanimaju.
O kolikom teleskopu (durbinu) se ovde prica?
(ako ne znas opticku moc onda reci bar koliko para si spreeman da
ulozis u to)
Tako ce biti mnogo lakse prporuciti bilo sta konkretno...
zvezde.8vstan,
Na danasnji dan pre 35 godina poleteo prvi covek u kosmos,
vazduhoplovni major Jurij Gagarin. Slava mu !
zvezde.10marija,
Ima li neko efemeride za Hale-Bopp kometu?
Marija
zvezde.11zormi,
* Ima li neko efemeride za Hale-Bopp kometu?
Čuo da će biti vidljiva krajem juna, ali efemeride nemam.
zvezde.12.andrew,
Marija, verovatno cemo uskoro dobiti na NO te efemeride te tako
se ne brini !
A ako treba pokusacu nekako da ih skinem sa NASSE
cU
zvezde.13.andrew,
ZANIMA LI VAS ASTRONOMIJA ILI MISTIKA ?
ZA TO POSTOJE GRUPE : ASTRONOMIJA I XFILES !
AKO STE ZAINTERESOVANI MAJLUJ TE MI !!
zvezde.14nenad,
Dva ruska astronauta će na stanici Mir provesti bar 40 dana više
nego što je planirano jer trenutno Rusi nemaju novca da izvrše
spuštanje.
Btw, srećno novo leto, kako smo proveli najkraću noć u godini? :)
zvezde.15.andrew,
Hvala, i tebi srecno leto !
Inace sam proveo na NO tj. Narodna Opservatorija
;)
cU
zvezde.16mango,
> Btw, srecno novo leto, kako smo proveli najkracu noc u godini? :)
Ludo, burazere, ludo;) (hint: crtac sa pevcom Sofronijem:)
zvezde.17dr.s,
/* Btw, srecno novo leto, kako smo proveli najkracu noc u godini? :)
Za udzbennikom... :( :)))))
zvezde.18micotakis,
Da li sam pogrešio mesto ili se ovde priča o Astrologiji?
Ili se ovde isključivo bavi astronomijom?
Ako sam na pravom mestu, interesuje me da li se neko profesionalno
bavi astrologijom, ili barem amaterski, ali da zna ponešto, a ne
samo da čita horskop u novinama.
EMPIRE
zvezde.19ilazarevic,
> Ili se ovde isključivo bavi astronomijom?
Zavisi koga pitaš. Ako pitaš mene, isključivo astronomijom.
zvezde.20vstan,
> Da li sam pogresio mesto ili se ovde prica o Astrologiji?
> Ili se ovde iskljucivo bavi astronomijom?
Pogresio si mesto. Ovde je iskljucivo AstroNOMIJA.
Za ono prvo predvidjeno je Razno (ili Misterije ;)
zvezde.21nothingman,
>> Pogresio si mesto. Ovde je iskljucivo AstroNOMIJA.
Da, ali se ovde proteklih meseci nije pisalo o astronomiji.
zvezde.22nenad,
> Mesec nema atmosferu, znači nema oblaka, znači moraju da se vide :)
Već je bila rasprava o ovome pre jedno dve godine, i tada sam
tvrdio (a tvrdim i dalje) da ne trebaju da se vide. Razlog je
jednostavan: kamere i foto-aparati su bili fokusirani na predmete
i astronaute. I u najzvezdanijoj noći kada osvetliš čoveka
kreflektorom i fotografišeš ga zvezde se neće videti.
zvezde.23vstan,
> Da, ali se ovde proteklih meseci nije pisalo o astronomiji.
Potrudicemo se :)
zvezde.24vstan,
> Razlog je jednostavan: kamere i foto-aparati su bili fokusirani na
> predmete i astronaute. I u najzvezdanijoj noci kada osvetlis
> coveka kreflektorom i fotografises ga zvezde se nece videti.
Pre je "problem" u onom drugom, dakle osvetljenje, a ne u
fokusiranju. Pri tako velikom kontrastu nema sanse da se
snime zvezde.
zvezde.25ilazarevic,
> jednostavan: kamere i foto-aparati su bili fokusirani na predmete
> i astronaute. I u najzvezdanijoj noći kada osvetliš čoveka
> kreflektorom i fotografišeš ga zvezde se neće videti.
Mislim da je problem u ekspoziciji. Da bi se snimile zvezde, potrebno je
nekoliko sekundi.
zvezde.26dr.s,
/* Mislim da je problem u ekspoziciji. Da bi se snimile zvezde, potrebno je
/* nekoliko sekundi.
Pa i Habl je slikao zvezde tako da slika izgleda kao da je
ekspozicija trajala dve nedelje. Drugacije nije moglo...
zvezde.27dr.s,
/* Mislim da je problem u ekspoziciji. Da bi se snimile zvezde, potrebno je
/* nekoliko sekundi.
HABL radi tako da ekspozicija bude dve nedelje.
Toliko o snimanju zvezda i sazvezdja...
zvezde.28vstan,
BESPLATAN KURS ASTRONOMIJE
U Planetarijumu Astronomskog društva "Ruđer Bošković"
započeo je dvoipomesečni besplatan kurs za ljubitelje
astronomije. Svakog petka i subote u isto vreme, do
sredine decembra, u bivšem amamu na Kalemegdanu
(ispod crkve Ružica) održavaće se predavanja iz ciklusa
"Astronomija za početnike", praćena slajdovima iz
oblasti o kojima će biti reč.
Na kraju kursa polagaće se ispit za buduće saradnike
Narodne opservatorije.
(Politika, 7.oktobar)
zvezde.29marco,
>> U Planetarijumu Astronomskog drustva "Ruder Boskovic"
>> zapoceo je dvoipomesecni besplatan kurs za ljubitelje
>> astronomije. Svakog petka i subote u isto vreme, do
Kad je poceo i u koje (isto) vreme?
zvezde.30vstan,
> Kad je poceo i u koje (isto) vreme?
Ne bih znao odgovor. Preneo sam ceo članak iz Politike.
Probaj da saznaš njihov tel. pa se raspitaj. Možeš i
nas da obavestiš :)
zvezde.31vstan,
>>> U Planetarijumu Astronomskog drustva "Ruder Boskovic"
>>> zapoceo je dvoipomesecni besplatan kurs za ljubitelje
>>> astronomije. Svakog petka i subote u isto vreme,
>
> Kad je poceo i u koje (isto) vreme?
Kursevi su od 17h. Sve što vas interesuje možete saznati na
tel.624-605 (Narodna opservatorija Kalemegdan).
zvezde.32vstan,
Danas je bilo pomračenje Sunca, oko 25%, od 16.50 pa do oko
17.50. Uvertira za sutrašnji smak sveta ?
zvezde.33nenad,
>> Kad je poceo i u koje (isto) vreme?
>
> Ne bih znao odgovor. Preneo sam ceo članak iz Politike.
Obično je počinjao početkom oktobra tako da je sada verovatno već
u toku. To nije kurs u klasičnom smislu, i osim ako neko baš
ne želi da polaže ispit na kraju može ponekad neobavezno otići na
predavanje, tj. senasu u planetarijumu. Kurs se inače ponavlja
svake jeseni i proleća, tako da ništa nije propušteno. Predavanja
su (bila) dva puta nedeljno, petkom i subotom popodne,
pretpostavljam da je i sada tako.
zvezde.34haevorn,
// vstan, 12.10.96. 19:32, 114 chr
//
// Danas je bilo pomračenje Sunca, oko 25%, od 16.50 pa do oko
// 17.50.
Pa što ne reče bar tri sata ranije? :((((
btw, taj smak sveta - po kom vremenu se računa? po našem ili
američkom (čuo sam da će biti između 12 i 13h ;))
zvezde.35biber,
>> Danas je bilo pomračenje Sunca, oko 25%, od 16.50 pa do oko
>> 17.50.
Što ne reče ranije :(
Oduvek sam voleo da gledam pomračenja. Sećam se kako sam kao
klinac čadio staklo, da bih gledao kroz. :)
zvezde.36vstan,
> // Danas je bilo pomračenje Sunca, oko 25%, od 16.50 pa do
>
> Pa što ne reče bar tri sata ranije? :((((
Da nisam slučajno pogledao kroz prozor ne bih ni ja video.
Danas piše da je počelo već oko 15.50. Zahvaljujući priličnoj
sumaglici moglo je lepo da se gleda bez pomagala.
zvezde.37vstan,
> Što ne reče ranije :(
> Oduvek sam voleo da gledam pomračenja. Sećam se kako sam kao
> klinac čadio staklo, da bih gledao kroz. :)
Nije bili najave u novinama, a tv ne pratim.
A moglo je lepo da se prati bez ikakvih "pomagala".
zvezde.38baker,
Izgleda da nas je ta "planeta" promasila !?
zvezde.39mileusna,
>> Što ne reče ranije :(
>> Oduvek sam voleo da gledam pomračenja. Sećam se kako sam kao
>> klinac čadio staklo, da bih gledao kroz. :)
Ako se ne varam, 11. avgusta 1999. godine nastupiće potpuno
pomračenje Sunca... Navij sat i uživaj... ;)
zvezde.40mileusna,
>> Izgleda da nas je ta "planeta" promasila !?
Zamalo... ;) Pitam se samo kako je nismo videli kad je
tolika, a ovaj mali tunjavi Mesec gledamo svake noći. :) Da nam
tako nešto zaista predstoji, ceo svet bi znao za to... Ili bi
možda krili da ne bi došlo do nereda na ulicama, a? :)
BTW, postoji i film na sličnu temu, kao meteor ide na
Zemlju, pa se ondak Rusi i Ameri dogovaraju da ga gađaju
nuklearnim bojevim glavama pripremljenim za rat zvezda itd.
Davno beše, ne sećam se detalja, ali znam da je New York
najeb'o na kraju... ;)
I setih se izjave Artura Klarka koji je rekao da sve što
se priča o posetama vanzemaljaca nije istina. Kada se isti
zaista pojave, rekao je, ceo svet će za to saznati u istom
trenutku... E sad, na šta je konkretno mislio ne znam. Da li
na to da će nas NASA sve obavestiti, ili jednostavno neće biti
moguće sakriti tako nešto...
zvezde.41lepiaf,
Film se zove Meteor.....
Le Piaf
zvezde.42marco,
>> BTW, postoji i film na slicnu temu, kao meteor ide na
A i knjiga, by Arthur C. Clarke "The Hammer of God"
Pisao sam matruski rad o toj knjigi :)
zvezde.43basrak,
> btw, taj smak sveta - po kom vremenu se računa? po našem ili
> američkom (čuo sam da će biti između 12 i 13h ;))
Ko je to uopšte provalio?
zvezde.44basrak,
>> Oduvek sam voleo da gledam pomračenja. Sećam se kako sam kao
>> klinac čadio staklo, da bih gledao kroz. :)
>
> A moglo je lepo da se prati bez ikakvih "pomagala".
Da li pomagala, tipa začađeno staklo, služe da bi se eliminisala svetlost ili
zračenja štetna po oko? Jer, kad je pomračenje totalno, onda svetlost nije
jaka, dapače, i može lepo da se gleda golim okom, ali je isto toliko opasno kao
što je i gledanje u Sunce bez pomračenja. Zato mislim da je gornja izjava malo
opasna. (?)
zvezde.45biber,
>> Da li pomagala, tipa začađeno staklo, služe da bi se eliminisala svetlost
>> ili zračenja štetna po oko? Jer, kad je pomračenje totalno, onda svetlost
>> nije jaka, dapače, i može lepo da se gleda golim okom, ali je isto toliko
>> opasno kao što je i gledanje u Sunce bez pomračenja. Zato mislim da je
>> gornja izjava malo opasna. (?)
Jedini razlog da se direktno ne gleda u Sunce je jaka
svetlost. Čak je i za vreme totalnog pomračenja, tj. dok je
ono još nepotpuno, svetlost izuzetno jaka.
zvezde.46basrak,
> Jedini razlog da se direktno ne gleda u Sunce je jaka
> svetlost.
Ja sam baš čuo suprotno. Nikako, ali nikako *ne* gledati u Sunce (čak ni kad je
pomračenje totalno (i potpuno)) golim okom, tj. bez ikakvih pomagala jer je
isto toliko opasno kao i gledanje u "obično" Sunce. Čak i opasnije jer zbog
drastično slabije svetlosti možeš duže gledati u njega, a UV i ostala zračenja
sa Sunca pi*e nesmetano.
Ajd' nek' neko od kolega astronoma razreši ovu, potencijalno vrlo opasnu,
dilemu...
zvezde.47ilazarevic,
> Ajd' nek' neko od kolega astronoma razreši ovu, potencijalno vrlo
> opasnu, dilemu...
Da vidimo šta na tu temu kaže kolega astronom Muhamed Muminović, "Praktična
astronomija".
"Sunce se može vizuelno posmatrati na više načina. No, prije nego što Vam
uopšte padne na pamet da ga gledate, pročitajte važno upozorenje. _Nikad ne
smijete gledati direktno u Sunce, ma kako mali teleskop bio._ Toplota koja se
stvara u fokusu može trajno oštetiti vid i čak izazvati sljepilo. Neki manji
komercijalni refraktori sadrže u svom priboru male filtere koji se
postavljaju ispred ili iza okulara. Autor knjige, iz vlastitog iskustva (a to
misli i većina drugih koji se bave posmatranjima) NE PREPORUČUJE OVAKVE
FILTERE. Jer, ma kako taman bio ovaj filter, ne možemo biti sigurni da li on
propušta infracrvene zrake koje su razorne, a koje ne vidimo. Takođe, usljed
toplote u fokusu, može da dođe do pucanja filtera kada je oko u djeliću
sekunde izloženo punom bljesku i toploti Sunca.
...
Veoma bezbedno možemo posmatrati Sunce pomoću specijalne "sunčeve prizme" ili
penta prizme. Zbog unutrašnjih refleksija svjetlosnih zraka, na okularni dio
teleskopa dolazi samo veoma mali dio ukupnog zračenja Sunca. Dovoljno je
koristiti neki obični filter i posmatranje je u potpunosti bezbjedno. ..."
Ovo se odnosilo na posmatranje pomoću instrumenata. Posmatranje golim okom bi
trebalo da bude slično, samo je opasnost manja za par redova veličine. Što se
čađavog stakla tiče, ja se ne bih usudio da ga koristim, jer kroz njega IC i
UV zraci prolaze nesmetano.
Naravno, ozbiljan posmatrač uvek bi napravio seriju fotografija.
P.S. Priznajem da bih gledao golim okom prstenasto pomračenje, ali samo dok
je u piku.
zvezde.51sale.car,
HI!
Posto vidim da je ovako 'malo' zaostala tema...
Ajde neka neko za pocetak obesi efemeride za ovu godinu (jesam
li se lepo odrazio ? :))
Ja sam letos gledao Jupiter sasvim lepo sa durbinom povecanja
20x.
Vide se i meseci...
Pozdrav...
zvezde.52vstan,
Juče je preminuo Karl Segan.
zvezde.53nenad,
> Juče je preminuo Karl Segan.
A sutra (subota) u 15:05:54 počinje zima.
zvezde.54fortuna,
Neka mu je vechna slava
zvezde.55lexus,
=>> Juče je preminuo Karl Segan.
=>
=> A sutra (subota) u 15:05:54 počinje zima.
Moram priznati da mi nije jasno kako uz vest o smrti
Karla Segana možeš da prilepiš vest o početku zime...
zvezde.56darth.vader,
>> Moram priznati da mi nije jasno kako uz vest o smrti
>> Karla Segana mozes da prilepis vest o pocetku zime...
Pa jel vidis da moze ;)
zvezde.57pifat,
Ko još nije saznao, evo email adrese Astronomskog društva
"Ru"er Bošković" i URL-a sa njegovim home page-om:
email: astrorbo@eunet.yu
http://solair.eunet.yu/~astrorbo
zvezde.58nenad,
Svetska saradnja u cilju eksploatacije teleskopa razlučivosti
1000 puta veće od one koju ima Hablov teleskop.
Uz poruku je i slika koja simbolizuje princip rada klastera radio
teleskopa, zbog čega se za ovaj i kaže da je "tri puta veći od
zemlje".
LAUNCH WILL CREATE A RADIO TELESCOPE LARGER THAN EARTH
NASA and the National Radio Astronomy Observatory are
joining with an international consortium of space agencies to
support the launch of a Japanese satellite next week that will
create the largest astronomical "instrument" ever built -- a
radio telescope more than two-and-a-half times the diameter of
the Earth that will give astronomers their sharpest view yet of
the universe.
The launch of the Very Long Base Interferometry (VLBI)
Space Observatory Program satellite by Japan's Institute of Space
and Astronautical Science (ISAS) is scheduled for February 10 at
8:50 p.m. Pacific time (1:50 p.m. February 11, Japan time.)
The satellite is part of an international collaboration
led by ISAS and backed by Japan's National Astronomical
Observatory; NASA's Jet Propulsion Laboratory (JPL); the National
Science Foundation's National Radio Astronomy Observatory (NRAO),
Socorro, NM; the Canadian Space Agency; the Australia Telescope
National Facility; the European VLBI Network and the Joint
Institute for Very Long Baseline Interferometry in Europe.
Very long baseline interferometry is a technique used by
radio astronomers to electronically link widely-separated radio
telescopes together so they work as if they were a single
instrument with extraordinarily sharp "vision," or resolving
power. The wider the distance between telescopes, the greater the
resolving power. By taking this technique into space for the
first time, astronomers will approximately triple the resolving
power previously available with only ground-based telescopes. The
satellite system will have resolving power almost 1,000 times
greater than the Hubble Space Telescope has at optical
wavelengths. The satellite's resolving power is equivalent to
being able to see a grain of rice in Tokyo from Los Angeles.
"Using space VLBI, we can probe the cores of quasars and
active galaxies, believed to be powered by super-massive black
holes," said Dr. Robert Preston, project scientist for the U.S.
Space Very Long Baseline Interferometry project at JPL.
"Observations of cosmic masers -- naturally-occurring microwave
radio amplifiers -- will tell us new things about the process of
star formation and activity in the heart of other galaxies."
"By the 1980s, radio astronomers were observing the
universe with assemblages of radio telescopes whose resolving
power was limited only by the size of the Earth. Now, through a
magnificent international effort, we will be able to break this
barrier and see fine details of celestial objects that are beyond
the reach of a purely ground-based telescope array. We anticipate
a rich harvest of new scientific knowledge from VSOP," Dr. Paul
Vanden Bout, director of NRAO.
In the first weeks after launch, scientists and engineers
will "test the deployment of the reflecting mesh telescope in
orbit, the wide-band data link from the satellite to the ground,
the performance of the low noise amplifiers in orbit, and the
high-precision orbit determination and attitude control necessary
for VLBI observations with an orbiting telescope," according to
Dr. Joel Smith, manager of the U.S. Space Very Long Baseline
Interferometry project at JPL. Scientific observations are
expected to begin in May.
The 8-meter (26-foot) diameter orbiting radio telescope
will observe celestial radio sources in concert with a number of
the world's ground-based radio telescopes. The 830-kilogram
(1,830- pound) satellite will be launched from ISAS's Kagoshima
Space Center, at the southern tip of Kyushu, one of Japan's main
islands, and will be the first launch with ISAS's new M-5 series
rocket.
The satellite will go into an elliptical orbit, varying
between 1,000 and 20,000 kilometers (620 to 12,400 miles) above
the Earth's surface. This orbit provides a wide range of
distances between the satellite and ground-based telescopes,
which is important for producing a high-quality image of the
radio source being observed. One orbit of the Earth will take
about six hours.
The satellite's observations will concentrate on some of
the most distant and intriguing objects in the universe, where
the extremely sharp radio "vision" of the new system can provide
much-needed information about a number of astronomical mysteries.
For years, astronomers have known that powerful "engines"
in the hearts of quasars and many galaxies are pouring out
tremendous amounts of energy. They suspect that supermassive
black holes, with gravitational fields so strong that not even
light can escape them, lie in the centers of these "engines."
However, the mechanism at work in the centers of quasars and
active galaxies remains a mystery. Ground-based radio telescopes,
notably NRAO's Very Long Baseline Array (VLBA), have revealed
fascinating new details in recent years, and VSOP is expected to
add a wealth of new information on these objects, millions or
billions of light-years distant from Earth.
Many of these same objects act as super-powerful particle
accelerators to eject "jets" of subatomic particles at nearly the
speed of light. Scientists plan to use VSOP to monitor the
changes and motions in these jets to learn more about how they
originate and interact with their surroundings.
The satellite also will aim at regions in the sky where
giant collections of water and other molecules act as natural
amplifiers of radio emission much as lasers amplify light. These
regions, called cosmic masers, are found in regions where new
stars are forming and near the centers of galaxies. Observations
can provide the detail needed to measure motions of individual
maser "spots" within these regions, and provide exciting new
information about the star-forming regions and the galaxies where
the masers reside. In addition, high-resolution studies of cosmic
masers can allow astronomers to calculate distances to them with
unprecedented accuracy, and thus help resolve continuing
questions about the size and age of the universe.
The project is a major international undertaking, with
about 40 radio telescopes from more than 15 countries having
committed time to co-observe with the satellite. This includes
the National Science Foundation's Very Long Baseline Array
(VLBA), an array of 10 telescopes spanning the United States from
Hawaii to Saint Croix; NASA's Deep Space Network sites in
California, Spain, and Australia; the European VLBI Network, more
than a dozen telescopes ranging from the United Kingdom to China;
a Southern Hemisphere array of telescopes stretching from eastern
Australia to South Africa; and Japan's network of domestic radio
telescopes.
In the United States, NASA is funding critical roles in
the VSOP mission at both JPL and NRAO. JPL has built an array of
three new tracking stations at its DSN sites in Goldstone,
California; Madrid, Spain; and near Canberra, Australia. A large
existing tracking station at each of these sites has also been
converted to an extremely sensitive radio telescope for
simultaneous observations with the satellite. JPL also is
providing precision orbit determination, scientific and
operational planning support to the Japanese, and advice to U.S.
astronomers who wish to observe with the satellite. NRAO is
building a new tracking station at Green Bank, West Virginia;
contributing observing time on the VLBA array of telescopes;
modifying existing data analysis hardware and software, and
aiding astronomers with the analysis of the VSOP data. Much of
the observational data will be processed at NRAO's facility in
Socorro, NM, using the VLBA Correlator, a special-purpose high-
performance computer designed to process VLBI data.
VSOP is the culmination of many years of planning and work
by scientists and engineers around the world. Tests using NASA's
Tracking and Data Relay Satellite System (TDRSS) proved the
feasibility of space VLBI in 1986. Just last year, those old data
were used again to successfully test the data-reduction
facilities for VSOP.
JPL manages the U.S. Space Very Long Baseline
Interferometry project for NASA's Office of Space Science,
Washington, D.C. The VLBA, headquartered in Socorro, New Mexico,
is part of the National Radio Astronomy Observatory, a facility
of the National Science Foundation, operated under cooperative
agreement by Associated Universities, Inc.
vlbi-2.gifzvezde.59nenad,
New Black-Hole Evidence
Astronomers from around the world braved the wintry elements to
gather in Toronto, Ontario, last week. Among the hundreds of
presentations was new evidence that binary star systems emitting
X-rays consist of recognizable stars orbiting black holes. V404
Cygni, a binary system 10,000 light-years away, gives off X-rays
as matter shed by its visible star heats up while rushing into
the black hole's gravitational well. But, according to Ramesh
Narayan and his colleagues, only a tiny fraction of the energy
expected from this infall seems to find its way out as visible
light or X-rays; the rest, they conclude, is being reabsorbed by
material which then falls into the black hole. Thus their model
may be showing that "event horizons" -- the one-way doors from
which energy and matter can never escape -- really exist.
zvezde.60nenad,
Europa's Eruptions
At a press conference on January 17th, NASA scientists presented
views of the enigmatic ice moon Europa that show features only 35
meters across -- roughly the size of a baseball diamond. The
jumble of cracks and ridges seen on a global scale continues in
ever-finer variation right down to the limit of resolution. More
important, some of the views reveal what appear to be eruptions
onto the surface from the interior. Based on their thickness, the
flows were not liquid water but had the consistency of thick
slush. In addition to ice volcanism, investigators can see that
the surface is modified by crustal spreading in some places and a
strange tectonic collapse in others. More and more evidence
suggests that Europa's outer crust is thin, perhaps only a few
kilometers thick in places, and that something else -- an ocean
or rock-ice-water slush -- lies just out of sight below.
zvezde.61nenad,
Novi najveći optički teleskop... :)
World's Largest Mirror
Opticians at Steward Observatory are now casting the world's
largest one-piece mirror blank, a giant monolith 8.4 meters (27.5
feet) across. It's all happening inside a giant oven that rotates
about seven times per minute, inside which the molten glass forms
a curved shape close to the desired final surface. Once the
casting is complete, the oven will continue to spin as the 20-ton
blank cools over the next few weeks. A second blank will be cast
later, and when finished the two mirrors will form the heart of
the Large Binocular Telescope
zvezde.62nenad,
Detaljnije o "susretima" letelice Galileo sa Evropom
ICE VOLCANOES RESHAPE EUROPA'S CHAOTIC SURFACE
Ice-spewing volcanoes and the grinding and tearing of
tectonic plates have reshaped the chaotic surface of
Jupiter's frozen moon Europa, images from NASA's Galileo
spacecraft reveal.
The images, captured when Galileo flew within just 692
kilometers (430 miles) of Europa on Dec. 19, were released
at a news briefing today at NASA Headquarters, Washington,
DC.
Although the images do not show currently active ice
volcanoes or geysers, they do reveal flows of material on
the surface that probably originated from them, said
Galileo imaging team member Dr. Ronald Greeley of Arizona
State University, Tempe, AZ.
"This is the first time we've seen actual ice flows on any
of the moons of Jupiter," said Greeley. "These flows, as
well as dark scarring on some of Europa's cracks and
ridges, appear to be remnants of ice volcanoes or
geysers."
The new images appear to enhance Europa's prospects as one
of the places in the solar system that could have hosted
the development of life, said Greeley.
"There are three main criteria to consider when you are
looking for the possibility of life outside the Earth --
the presence of water, organic compounds and adequate
heat," said Greeley. "Europa obviously has substantial
water ice, and organic compounds are known to be prevalent
in the solar system. The big question mark has been how
much heat is generated in the interior.
"These new images demonstrate that there was enough heat
to drive the flows on the surface. Europa thus has a high
potential to meet the criteria for exobiology," Greeley
added.
"This doesn't prove that there is an ocean down there
under the surface of Europa, but it does demonstrate that
it is a scientifically exciting place," said Galileo
imaging team member Dr. Robert Sullivan, also of Arizona
State University.
The images also reveal a remarkable diversity in the
geological age of various regions of Europa's surface.
Some areas appear relatively young, with smooth,
crater-free terrain, while others contain large craters
and numerous pits, suggesting that they are much older.
The icy crust bears the signs of having been disrupted by
the motion of tectonic plates. "There appear to be signs
of different styles of tectonism," said Greeley. "In many
areas we see that the crust was pulled apart in a
spreading similar to the processes on the sea floor on
Earth. This is different from the tectonic processes at
work on, say, Jupiter's moon Ganymede. This suggests that
Europa's interior may be different from Ganymede's."
Galileo scientists will have a better chance to understand
Europa's interior when the spacecraft gathers gravity data
on another flyby next November. The gravity field is
measured by tracking how the frequency of Galileo's radio
signal changes as it flies past the moon. This was not
possible during the recent flyby because radio conditions
were degraded as Jupiter passed behind the Sun from
Earth's point of view.
Europa is crisscrossed by an amazingly complex network of
ridges, said Sullivan. "Ridges are visible at all
resolutions," he explained. "Closely paired ridges are
most common. With higher resolution, ridges seen
previously as singular features are revealed to be
double."
Some of the ridges may have formed by tension in the icy
crust: as two plates pull apart slightly, warmer material
from below might push up and freeze to form a ridge. Other
ridges may have been formed by compression: as two plates
push together, the material where they meet might crumple
to form the ridge.
In addition to ice flows and tectonics, Greeley and
Sullivan noted that some areas on Europa seem to have been
modified by unknown processes that scientists are still
debating.
Greeley said that some areas, for example, seem to have
been modified by "sublimation erosion" -- the evaporation
of water and other volatiles such as ammonia and methane
into the vacuum of space. "Something is destroying the
topography," said Greeley, "and this sublimation erosion
is a good candidate for what is at work."
During last month's encounter, Galileo flew more than 200
times closer to Europa than the Voyager 2 spacecraft did
in 1979. After a swing past Jupiter next week in what
mission engineers call a "phasing orbit," Galileo's next
targeted flyby will take it again past Europa as it passes
within 587 kilometers (364 miles) on February 20.
zvezde.63nenad,
Idemo na Saturn... :)
CASSINI PROGRAM STATUS
Having successfully completed recent space environmental
tests, NASA's Cassini spacecraft, destined for the planet Saturn,
has been returned to JPL's spacecraft assembly facility for a
final round of systems testing.
The program remains on schedule and within budget.
The spacecraft, due for launch Oct. 6, will be shipped this
spring to NASA's Kennedy Space Center in Florida for pre-launch
preparations.
Cassini last week completed a month of so-called "shake
and bake" tests that imitate the vibration forces and extreme
temperatures the spacecraft will have to withstand during its
upcoming launch and flight through space. Reflective gold-
colored space blankets have been sewn and laced into place on the
Saturn orbiter. The 24-layer blankets will protect Cassini's
computers and other systems from the extreme hot and cold of
space.
The painstaking assembly of Cassini, the most
sophisticated U.S. planetary spacecraft ever built, has been
under way at JPL since 1995. Development of the mission began in
1989 and has involved the efforts of thousands of people at
university and government research labs and technology and
business firms across the country. In Europe, work continues on
the Huygens probe that will be mounted on Cassini and dropped via
parachute to the surface of Saturn's largest and most mysterious
moon, Titan. The Huygens probe will be mated with the Cassini
spacecraft at Kennedy Space Center in late spring.
After a nearly seven-year trip, Cassini will reach Saturn
in July 2004. There, it will enter orbit around the ringed planet
and make detailed, four-year observations of Saturn, its largest
moon Titan, several smaller icy moons, and the magnetic
environment surrounding the planet. The Huygens probe destined
for Titan's surface is provided by the European Space Agency
(ESA). The probe will parachute to the surface of Titan, thought
to resemble an early Earthlike environment before life began. The
mission is an international effort of NASA, ESA and the Italian
Space Agency (ASI), and is managed for NASA by JPL.
zvezde.64nenad,
Hubble Servicing Mission Under Way
Early on February 14th a pair of space-walking astronauts aboard
the shuttle Discovery successfully installed two new instruments
on the Hubble Space Telescope. The one dubbed NICMOS
(Near-Infrared Camera and Multi-Object Spectrometer) will explore
the universe at infrared wavelengths longer than 1 micron. The
other package, called STIS (Space Telescope Imaging Spectrograph)
can obtain the spectra of many objects simultaneously. Project
scientists say the instruments have passed a "liveness" test but
that it will be several weeks before all their systems can be
checked out. STIS, for example, operates with a high-voltage
power supply that can't be turned on until air inside the
instrument has been completely evacuated. Look for the first
press conference to show off new results in early May
zvezde.65nenad,
Novi rezultati pokazuju da su Plejade bliže nego što se mislilo,
ali i da je svemir za oko 10% veći.
Early Results from Hipparcos
Today European astronomers announced a series of results from the
Hipparcos mission, though the full data set will not be made
public until June. Launched in August 1989, the spacecraft spent
several years measuring the positions and brightnesses of stars
down to magnitude 11 with unprecedented accuracy. Among the new
findings is that the Pleiades star cluster appears to be about 10
percent nearer than previously thought. Hipparcos data pegs the
distance at 360 light-years. Also Cepheid variables, the
pulsating stars that astronomers use to gauge the distances to
other galaxies, are intrinsically more luminous -- and thus
farther away -- than believed. This implies that the universe may
be larger than previous estimates by about 10 percent, and also
that the most distant (and thus oldest) stars are no more than
about 11 billion years old. Cosmologists should find that good
news, since they now estimate that the universe as a whole is
some 12 billion years old.
zvezde.66vstan,
Dok ne stignu novi snimci sa Evrope evo tri
stara snimka.
evropa.zipzvezde.67morkin,
> Europa's Eruptions
> strange tectonic collapse in others. More and more evidence
> suggests that Europa's outer crust is thin, perhaps only a few
> kilometers thick in places, and that something else -- an ocean
> or rock-ice-water slush -- lies just out of sight below.
Još samo da sačekamo da na Mesecu otkriju "crni objekat" čije su dimenzije u
odnosu 1:4:9...
zvezde.68space.ace,
>> Još samo da sačekamo da na Mesecu otkriju "crni objekat" čije su dimenzije
>> u odnosu 1:4:9...
Za to ćeš morati da sačekaš do 2001...
zvezde.69nenad,
Does 51 Peg's Planet Really Exist?
According to David Gray, an astronomer at the University of
Western Ontario, the planet-size companion to the star 51 Pegasi
does not exist. This is the star that started the current rush of
extrasolar planet discoveries back in 1995. Astronomers Michel
Mayor and Didier Queloz then claimed that subtle shifts in the
star's spectrum show that it is nodding back and forth relative
to Earth, the effect of an object with at least half Jupiter's
mass circling nearby every 4.2 days. But Gray, who is an expert
on stellar spectroscopy, believes that the star itself is causing
the effect. He found that the shape of an absorption line was
tilting one way, then the other, in lock step with the putative
planet's orbit. Orbital motions can't change the shape of a
spectral line, only its position. "Therefore," Gray wrote in
Nature for February 27th, "the planet hypothesis is no longer an
adequate interpretation of the data." Instead, says Gray, 51
Pegasi seems to undergo complex pulsations that somehow tilt the
lines back and forth. However, planet-hunters are rising to 51
Peg's defense, arguing that the pulsations Gray envisions can't
become strong enough to reproduce the observed behavior. The
outcome of this debate will affect the viability of planets
presumed to circle three other stars too.
zvezde.70nenad,
Pioneer 10's Silver Anniversary
March 2nd marks the 25th anniversary of the launch of Pioneer 10.
A product of NASA's Ames Research Center, it might be called the
"Energizer Bunny" of interplanetary spacecraft. It's now almost
exactly 10 billion kilometers from Earth, more than 9 light-hours
away. Pioneer 10 made history with its close flyby of Jupiter in
December 1973. Along with Pioneer 11, which arrived the following
year, this 570-pound spacecraft took many pictures of Jupiter and
its major moons. But the twin spacecraft will be most remembered
for their measurements of the fields and charged particles in
Jupiter's immense magnetosphere.
The 260-kilogram spacecraft was equipped with 11 instruments,
only one of which continues to operate.
zvezde.71nenad,
COOL, SAFE, COMPACT, LIGHT, EFFICIENT, NON-POLLUTING New JPL-USC
Methanol Fuel Cell Shows Promise For Zero-Emission Vehicles
A revolutionary design for a cool-process, zero-emission
methanol fuel cell just patented by Caltech's Jet Propulsion
Laboratory and the University of Southern California is already
under fast-track development for a wide range of uses.
In one major project, developers believe they can create a
unit about the size of a thick paperback book that can run
continuously for weeks at a time, producing 50 watts of power,
consuming about a pint of methanol fuel per day, and emitting
only water and carbon dioxide.
The technology, whose development was funded by the U.S.
Defense Advanced Research Projects Agency (DARPA) and private
sources, is easily scaleable into larger units capable of
powering portable non-polluting electronic equipment or,
eventually, zero-emission motor scooters or cars. The U.S.
military is interested in the technology for its potential of
providing portable power to soldiers in the field.
A private sector corporation, DTI Energy, Inc.,
headquartered in Los Angeles, has licensed the technology and
intends to develop and sublicense various prototypes and
applications. It has initially designed units of up to 5 kilowatt
output, powerful enough to run a light-duty vehicle.
"This fuel cell may well become the power source of choice
for energy-efficient, non-polluting electric vehicles," said JPL
fuel cell team manager Gerald Halpert. "This invention also has
vast potential to improve the environment by providing clean
energy in portable form," noted Nobel prize-winning chemist
George Olah of USC, one of the co- inventors.
Like all fuel cells, the JPL/USC device, called a "Direct
Methanol, Liquid Feed Fuel Cell," converts the chemical energy of
its fuel directly into electrical current without burning the
fuel. It has many remarkable advantages:
- It uses the common and widely used substance, methanol
(a liquid also known as methyl alcohol) as the base fuel mixed
with water. Methanol is inexpensive (currently, approximately 40
cents per gallon), easily manufactured from coal or natural gas,
and safe to store--existing gas stations could easily sell it.
- It runs relatively cool--below the boiling point of
water- -and is compact. Existing fuel cells typically operate at
high temperatures, some at temperatures hot enough to melt many
metals, thus requiring bulky thermal insulation and structural
reinforcement to mitigate safety hazards.
- It creates no toxic byproducts whatsoever. The methanol
fuel is completely converted to carbon dioxide (CO2 ) and water.
- It is simple and relatively inexpensive to manufacture,
consisting of little more than a membrane coated with platinum or
other noble metals. The cell itself has no moving parts. Its
precious metals are used in small amounts and can be completely
recovered and recycled at the end of the device's life.
- It is efficient. In its existing configuration, it
converts more than 34 percent of the theoretical energy content
of the fuel into usable power. This is twice the efficiency of
existing gasoline engines. Developers believe that improvements
now on the drawing board will push the efficiency to more than 45
percent of theoretical energy content.
A U.S. patent for an "aqueous liquid-feed organic fuel
cell using solid polymer electrolytic membrane" was issued early
this month with Caltech, JPL's parent organization, and USC as
joint patent holders.
"In addition to not polluting the environment," noted
JPL's Dr. Subbarao Surampudi, who supervises JPL's
Electrochemical Technologies Group, "we believe that cells of
this design can replace batteries in many applications and
provide reliable emergency power in disasters." Battery
manufacturing involves toxic materials, so the disposal of used
batteries has become a major problem, scientists note.
Prototype cells have been assembled and tested at JPL.
According to Dr. Halpert, these models have run for more than 200
hours continuously at JPL and for more than 3000 hours
intermittently--equivalent to approximately 150,000 miles--at
partner Giner Inc.'s labs without loss of performance. Current
design goals envision units that can operate continuously for
1000 or more hours, and, eventually, units that can produce the
40 kilowatts or more required to power a full-sized car. "The
system's simplicity as a clean-energy alternative to the use of
fossil fuel-powered combustion engines will generate widespread
appeal in the automotive industry," predicts Halpert.
The fuel cell's design is quite simple. A membrane divides
the cell in half, with methanol fuel in water on one side and
gas, either oxygen or air, on the other. The membrane is coated
on both sides with a special, electrochemically active catalytic
coating developed by JPL. The liquid side is the anode.
Methanol--a molecule consisting a single carbon atom linked to
three hydrogen atoms and one oxygen-hydrogen (hydroxyl) group--
spontaneously reacts at the catalytic surface. In this reaction,
the carbon-hydrogen bonds are broken. The hydrogen atoms lose
their electrons and become protons, also known as hydrogen ions,
and migrate across the membrane to the gas side, the cathode.
There, on the cathode's catalytic surface, they combine with
oxygen from the air to produce water. The electrons given up on
the anode side generate the current.
The carbon left on the liquid side is completely converted
into non-toxic carbon dioxide. The cell is fuel-versatile,
operating on methanol-derived fuels.
"A major problem with the existing device, however, is
that the membrane used allows not just protons to cross to the
cathode side, but also methanol, thus degrading performance,"
according to Sekharipuram R. Narayanan, who spearheaded the
catalyst development work.
The Loker Institute's Drs. Prakash, Olah, Qungie Wang and
Marshall Smart, along with JPL's Drs. Narayanan, Surumpudi and
Halpert, have pioneered the development of improved proton
membranes that will permit the construction of a new generation
of cells achieving greater efficiency by blocking methanol
migration. USC and JPL have applied for patents on these new
membranes. The research team also hopes to drastically cut the
cost of the proton exchange membrane, which is currently very
expensive, the major economic roadblock to widespread
applications.
Prakash, a professor in the department of chemistry in the
University of Southern California's College of Letters, Arts and
Sciences and at the Donald P. and Katherine T. Loker Hydrocarbon
Institute, has collaborated with Dr. Olah, the Institute's
director, for decades. Olah was awarded the Nobel Prize in
chemistry in 1994 for his work with superacids, similar to
substances used in the creation of the methanol fuel cell
membrane.
Olah has long maintained that chemistry can provide
solutions to environmental problems while maintaining economic
growth without destructive effects. "Both George and I think that
this fuel cell is a prime example of this belief," said Prakash.
It was Prakash who in 1989 approached Surampudi of JPL
seeking expertise in electrochemistry to design the cell and
electrocatalysts to make the system work. Anthony Laconti, John
Kosek and Cecilia Cropley of Giner Corp. were also involved in
the development of the cell. "We think this new technology will
bring the fuel cell down to earth for good," Prakash added.
JPL/USC, together with Giner Corp., is working on a
contract from the Department of Defense to develop a 50-watt
methanol fuel cell to replace lithium batteries used in various
Department of Defense applications; a 150-Watt development
program will begin in April, 1997. Other government entities
involved include the Army Research Office and the Army Research
and development command.
Harvey Frank, one of the co-inventors, has been working on
fuel cells since 1960. Starting in 1989, the methanol fuel cell
work was conducted by chemists Olah and Surya Prakash of USC and
developed in cooperation with JPL researchers Halpert, Surampudi,
Narayanan and Eugene Vamos, as well as the support of JPL team
members Thomas Valdez, Andrew Kindler, Elizabeth Yen, William
Chun, Barbara Nakamura and Albany Lee.
Licensee DTI Energy Inc. intends to develop a hybrid
system for vehicular applications, according to President Todd
Marsh. The fuel cells will be used to recharge continuously both
conventional batteries and more advanced batteries, extending the
range of the vehicles they power. "As we develop expertise in
this area," he explained, "we will concurrently be developing a
full range of applications, including stand-alone power, power
generators, uninterrupted power supplies, and consumer electronic
battery replacement, among others."
JPL's Technology Affiliates Program, which made the
technology available for license to DTI Energy Inc., is designed
to help U.S. companies improve their competitive positions in the
global economy by transferring JPL technology into the
marketplace. U.S. industry may tap the commercial potential of
JPL's technology development activities via mechanisms ranging
from reports, seminars, patent and software licenses to direct
interaction with laboratory technologists. The nine-year-old JPL
program now includes nearly 120 companies and has facilitated
more than 200 technology transfer projects to benefit companies
and the public.
zvezde.72morkin,
> "Energizer Bunny" of interplanetary spacecraft. It's now almost
> exactly 10 billion kilometers from Earth, more than 9 light-hours
> away. Pioneer 10 made history with its close flyby of Jupiter in
A gde je sada? Jel još između Neptuna i Plutona? Koliko ima do Plutona?
zvezde.75zormi,
*> "Energizer Bunny" of interplanetary spacecraft. It's now almost
*> exactly 10 billion kilometers from Earth, more than 9 light-hours
*> away. Pioneer 10 made history with its close flyby of Jupiter in
*
* A gde je sada? Jel još između Neptuna i Plutona? Koliko ima do Plutona?
Trenutno je otprilike dvostruko dalje od nas nego Pluton (koji nam je
inače do 1999 god malo bliži od Neptuna jer mu orbita preseca Neptunovu).
Pluton je inače udaljen 30-50 AU (astronomskih jedinica = razdaljina
Zemlja-Sunce = oko 150 mil.km) dakle ima jako ekscentričnu putanju,
ali je sonda daleko iza i njegovog krajnjeg dometa.
zvezde.76nenad,
> A gde je sada? Jel još između Neptuna i Plutona? Koliko ima do Plutona?
Meni se čini da je pre neku godinu izašao iz okvira orbite
Plutona i napustio sunčev sistem.
zvezde.77morkin,
> inače do 1999 god malo bliži od Neptuna jer mu orbita preseca
> Neptunovu).
Po toj logici, jednog dana će se sudariti. Zna li se kada (za koliko miliona
godina)?
> ali je sonda daleko iza i njegovog krajnjeg dometa.
Da li šalje neke signale? Pisalo je da radi samo jedan uređaj. Koji?
Ja baš zaređao sa pitanjima...
zvezde.78zormi,
*> inače do 1999 god malo bliži od Neptuna jer mu orbita preseca
*> Neptunovu).
*
* Po toj logici, jednog dana će se sudariti. Zna li se kada (za koliko
* miliona godina)?
Teško. Svemir je suviše veliki, orbita Plutona je vrlo nagnuta
i ne kači direktno Neptunovu, Pluton obidje Sunce za nekih 250
godina a Neptun za (zaboravio sam tačno) stotinak pa da se baš
susretnu i pogode...
*> ali je sonda daleko iza i njegovog krajnjeg dometa.
*
* Da li šalje neke signale?
Šalje još signal ali je isti bar 50 dB ISPOD nivoa kosmičkog šuma
tako da se teško izvlači i mala je propusna moć. Uglavnom se radi
o merenjima solarnog "vetra" i magnetnog polja. Pored toga što je
sonda sve dalje od nas pa signal slabi, sve je dalje i od Sunca
koje napaja njene baterije (ne znam koji će uredjaj ostati poslednji
da troši rezerve, mogu da potražim). Sa te daljine Sunce je naj-
sjajnija zvezda na nebu - ali ništa više od toga.
Uskoro će potpuno isključena sonda ohladjena na svega par stepeni
iznad apsolutne nule nastaviti put ka zvezdama i za 30000 godina
proći pored jedne slabašne zvezdice. Jedina funkcija koja joj
preostaje je funkcija glasnika, odnosno činjenica da postoji, da
je napravljena na Zemlji i da je stigla toliko daleko. Na sebi ima
i ploču sa ugraviranim raznim simbolima o Zemlji i čoveku za slučaj
da je neko presretne (posle najnovije serije SF filmova možda je
bilo bolje detonirati neku ugradjenu bombu dok je još u dometu ;)
zvezde.79nenad,
Hale-Bopp Spins Its Magic
Recent observations by European astronomers using the 1-meter
telescope at Pic du Midi Observatory in France show that Comet
Hale-Bopp (C/1995 O1) rotates every 11.47 hours, but that the
spin rate actually varies by about a half hour over a three-week
period. This complex rotation, which may include precession, is
combining with a prominent jet or jets of dust to create the
multiple bright shells that have been observed on the sunward
side of the nucleus. The comet will be closest to the Earth on
March 22nd (197 million kilometers) and to the Sun on April 1st
(137 million km).
zvezde.80nenad,
Nova letelica namenjena kruženju oko Meseca je spremna, biće
lansirana u septembru. Uz poruku je njen crtež.
Lunar Prospector Rollout
On March 12th project officials showed off the completed Lunar
Prospector spacecraft at Lockheed-Martin in Sunnyvale,
California. Costing a total of $63 million, the mission is set
for launch on September 24th. Lunar Prospector will circle the
Moon for a year, studying magnetic fields, gravity, and surface
characteristics. One key experiment will look for telltale
neutrons emitted by water ice thought to lie in the permanently
shadowed lunar poles.
lp01.jpgzvezde.81nenad,
Noćas je Mars u opoziciji, ovih dana je najbolje vreme ako želite
da ga gledate. Uz poruku je jedna skorašnja slika marsa sa
Hablovog svemirskog teleskopa.
Mars at its Best
The red planet reaches opposition on March 17th, when it rises
around sunset and shines all night. Although ever so slightly
dimmer than Sirius at magnitude -1.3, Mars will attract more
attention -- partly because it stares steadily at us with little
or no twinkling and shines with a distinctive, orange-gold light.
It will gain special notice above the almost totally eclipsed
Moon on the night of March 23rd. The Martian disk appears 14
arcseconds across, tipped slightly so that its north pole is in
view.
marshst.gifzvezde.82nenad,
A 20. marta u 5 minuta do 3 popodne počinje proleće. :)
March Equinox
Spring returns to the Northern Hemisphere, and autumn to the
Southern, at 13:56 Universal Time on March 20th. At that moment
the Sun crosses the celestial equator as it moves northward among
the stars.
zvezde.83pdeze,
Pozdrav!
Gde se moze videti Hale Bopp ovih dana?
P.S. Nisam bas u toku otkad sam potrosio vreme na internetu :(
zvezde.84zormi,
* Gde se moze videti Hale Bopp ovih dana?
Posle zalaska Sunca (oko 19h) ka zapad-severozapadu negde 20-tak stepeni
iznad horizonta, nećeš promašiti...
zvezde.85stameni,
>> * Gde se moze videti Hale Bopp ovih dana?
>>
>> Posle zalaska Sunca (oko 19h) ka zapad-severozapadu negde 20-tak
>> stepeni iznad horizonta, nećeš promašiti...
Zna li ko u kom je sazvežđu? Ja mislim Zmijonoša, ali nisam
siguran...
zvezde.86nenad,
> Gde se moze videti Hale Bopp ovih dana?
The Great Comet of 1997 is now entering "prime time." The
twin-tailed spectacle is obvious in both the morning and evening
skies from midnorthern latitudes. Comet Hale-Bopp sports a long,
thin, faint gas tail and a shorter, broader, brighter dust tail.
The interplanetary interloper comes closest to Earth on March
22nd, though it will be on the far side of the Sun and 197
million kilometers away at the time. Over the following two days
the comet sails just 5 degrees north of M31, the Andromeda
Galaxy. The comet's total visual magnitude is now about -0.5. To
see Comet Hale-Bopp at its best you should look at least 1╝ hours
before sunrise or after sunset, though its starlike inner coma
can still be seen in twilight. It's about 20░ above the
northeastern horizon before dawn, and roughly the same height
above the northwestern horizon in the evening.
zvezde.87nenad,
> Zna li ko u kom je sazvežđu? Ja mislim Zmijonoša, ali nisam
> siguran...
Na ovoj slici se vidi po danima gde će se nalaziti i moći videti
u večernjim časovima.
marpm2.jpgzvezde.88nenad,
> Zna li ko u kom je sazvežđu? Ja mislim Zmijonoša, ali nisam
> siguran...
...a na ovoj gde se može videti u jutarnjim časovima, takođe po
danima.
maram2.jpgzvezde.89nenad,
A za one zainteresovane šta učene glave misle i rade po tom
pitanju (Hale-Bopp kometa), evo i te informacije. :)
ULYSSES SCIENTISTS BEGIN CAPTURING UNIQUE VIEW OF HALE-BOPP
Scientists on a joint NASA-European Space Agency mission
to study the poles of the Sun are using the Ulysses spacecraft's
unique, high latitude orbit to help understand changes in comet
Hale-Bopp as it nears the lower latitudes of the Sun while
spewing its outer layers of gas and dust.
Using solar wind data from the spacecraft, a team of
interdisciplinary scientists at NASA's Jet Propulsion Laboratory,
the University of Colorado at Boulder and an international group
of amateur astronomers known as the "Ulysses Comet Watch" have
been observing other comets in the same way as they return from
the far reaches of space. This unique, collaborative research
effort focuses specifically on what happens to comets as they are
exposed to different solar wind conditions at various solar
latitudes.
"Until recently, no spacecraft had flown through high
latitudes above the Sun's equator and the properties of the solar
wind at these latitudes could only be surmised," said Dr. Edward
Smith, project scientist of the Ulysses mission at JPL. "In the
last two years, Ulysses has studied the steady, high-speed winds
at high latitudes, and alternating, slow and fast winds near the
Sun's equator. Hale-Bopp is about to enter the lower latitude
zone, where the disturbed solar wind resides, and where dramatic
changes in the comet's plasma tail are expected to occur."
The Ulysses Comet Watch group, spearheaded by Drs. John C.
Brandt and Martin Snow of the University of Colorado's Laboratory
for Atmospheric and Space Physics, and Carolyn Collins Petersen,
now of Sky Publishing Corp. in Cambridge, MA, will provide
worldwide observations of the returning comet as it descends from
the polar regions of the Sun. Images from more than 200 observers
around the world will be posted on the Ulysses Comet Watch home
page on the Internet at http://lasp.colorado.edu/ucw/.
Observations will continue to be posted well after the comet
makes its closest approach to the Sun on April 1.
The Ulysses group is not watching for changes in the
comet's more visible, wider and yellowish dust tail, though, but
rather for changes in its narrower, paler, often bluish plasma
tail, which consists of ionized gas being emitted by the comet
and picked up by the magnetic field being swept along by the
solar wind.
"We are particularly interested in the comet's plasma
tail, which 'turned on,' or began to outgas, when Hale-Bopp was
about 1.5 astronomical units (140 million miles) from the Sun,
the equivalent of 1.5 times the distance between the Earth and
the Sun," Brandt said.
Cometary plasma tails change constantly due to their
interactions with slow and high-speed solar wind. One of the more
dramatic changes that can occur is the abrupt disconnection of
the tail, which then drifts away. Often a new tail will form
within hours.
"Comets lose their plasma tails when they are subjected to
abrupt reversals in the direction of the solar wind magnetic
field," Smith said. "This magnetic field reversal typically
happens in the equatorial regions twice per solar rotation, or
about every 13 days. They don't occur at high latitudes."
Consequently, Brandt and his team expect to see such
dramatic changes in the comet's plasma tail only in the
equatorial regions of the solar wind -- between 20 degrees north
and 20 degrees south of the Sun's equator.
Modeled after the very successful international Halley
Watch observation networks, which operated during 1985 and 1986,
the Ulysses Comet Watch network has been operating since late
1992. Observers have studied a number of comets, and have
supplied sequences of high-quality images of comets de Vico,
which returned in September 1995, and Hyakutake, which was
discovered and observed last year.
Scientists first discovered that the plasma tails of these
comets change and drop off according to their latitudes with
respect to the Sun during these two comet returns. Observers are
now beginning to submit early images of Hale-Bopp, which,
according to Brandt, are looking equally as promising. "In fact,
we expect the network's output of Hale-Bopp images to be
fantastic," he said.
"At equatorial latitudes, the solar wind moves at an
average speed of about 450 kilometers per second (970,000 miles
per hour) with large variations in speed and density," Brandt
continued. "This type of wind apparently comes from the
equatorial streamers so clear at solar eclipses. The plasma tail
of a comet experiencing this part of the solar wind has a
distinctly disturbed appearance which varies over time, and
undergoes disconnection events as it experiences reversals of the
magnetic field.
"By contrast, when the same comet travels through the
polar latitudes, it encounters a more steady, less dense and
faster solar wind, moving at about 750 kilometers per second or
1.6 million miles per hour," Brandt said. "There are smaller
variations in speed and density and no magnetic field reversals.
Consequently, the plasma tail looks much less turbulent and does
not have disconnection events. So, the comet, by acting as a
'solar wind sock,' can be used to map the conditions in different
latitudes of the solar wind."
Comet Hale-Bopp is ideally suited to show these types of
tail changes because of its high-latitude orbit. Ulysses'
measurements of the solar wind from the same latitude, combined
with ground-based observations of comet tails, will help
scientists better understand the physics involved in cometary
gases and their interaction with the outward-flowing solar wind.
From this information, they may be able to understand the solar
wind in regions that have never been accessible to spacecraft
before, such as very close to the Sun or at much higher latitudes
above and below the Sun's equator.
zvezde.90nenad,
Sutra uveče, odnosno iz Evrope prekosutra ujutru biće moguće
videti pomračenje Meseca.
A Deep Partial Lunar Eclipse
Skywatchers almost everywhere in the Americas will have a fine
view of the Moon being eclipsed on the night of March 23rd, if
the weather is clear. Viewed from Europe and Africa, the Moon
will be in the western sky before or during dawn on the morning
of the 24th. Adding to the scene will be the bright orange planet
Mars about 12° above or to the upper right of the Moon. Here are
Eastern Standard Times of the major events: Partial eclipse
begins at 9:58 p.m.; mid-eclipse is at 11:39 p.m.; partial
eclipse ends at 1:21 a.m. March 24th (convert these to your local
time zone).
zvezde.91nenad,
Naučnici još uvek ispituju fosilne ostatke pronađenje na
meteoritu koji potiče sa Marsa, ali po svemu sudeći to njihovo
istraživanje neće dovesti ni do kakvih konačnih zaključaka.
Life on Mars Revisited
Planetary scientists gathered in Houston, Texas, this week to
debate the likelihood that life existed on Mars billions of years
ago. The focus of their attention was a Martian meteorite
designated ALH 84001. Last August, scientists from NASA and
Stanford University built a case for microscopic fossils within
the 4-pound stone, and at the Houston meeting more that 30 papers
detailed new studies of the rock. The life hypothesis hinges in
part on the origin of bits of carbonate minerals within which the
putative fossils were found. Several presenters maintained that
the carbonates formed slowly at temperatures below the boiling
point of water. But others argued that the minerals came together
while at several hundred degrees -- much too hot to sustain any
known organisms.
Meanwhile, several research teams have searched for chemical
fingerprints of life, and whether ultramicroscopic structures are
fossilized microbes or just flecks of mineral. As NASA scientist
Doug Blanchard summed up, "It's still too early to conclude about
life on Mars -- no one knows the truth just yet." NASA and the
National Science Foundation plan to distribute more samples of
the unique meteorite next month, to begin a new round of tests by
scores of scientific teams worldwide.
zvezde.92nenad,
A Binary's Dust Disk
Using a coronagraphic camera on Mauna Kea, astronomers have found
what may be a gigantic disk of dust, some 2 trillion kilometers
in diameter, surrounding BD +31°643, an 8th-magnitude binary star
1,100 light-years distant in the constellation Perseus. Dust
disks or shells have been indirectly discerned around dozens of
stars via infrared spectral measurements. But, until now,
astronomers had only managed to "photograph" such a feature
around one main-sequence star, Beta Pictoris. In Nature for March
6th, Paul Kalas (Max-Planck Institute for Astronomy) and David
Jewitt (University of Hawaii) surmise that the newfound disk
would require a Jupiter's worth of planetesimals, which create
dust by smashing into one another, to sustain itself. If each of
these putative colliders were a typical large rocky asteroid, 100
km across, at least a billion such objects must swarm around the
binary's two B-type stars. Kalas's upcoming Hubble Space
Telescope observations will inspect the enigmatic disk with 10
times better resolution than the discovery image.
zvezde.93guta,
U čast Hale-Bopp komete, prenosim nekoliko sličica sa NASA site-a.
Uz ovu poruku je slika zamišljenog udara komete u Zemlju - u pitanju
je umetnički prikaz, i fenomenalno izgleda.
comet.jpgzvezde.94guta,
Još jedan prikaz udara komete u Zemlju, NASA site.
earth.gifzvezde.95guta,
U arhivi uz poruku se nalazi 11 slika Hale-Bopp komete, u raznim
stadijumima približavanja Zemlji, pored koje sada prolazi. Lepo se
može videti formiranje repova kako se kometa približava Suncu.
halebopp.zipzvezde.96vlajel,
*>
*> U arhivi uz poruku se nalazi 11 slika Hale-Bopp komete, u
*> raznim stadijumima približavanja Zemlji, pored koje sada
*> prolazi. Lepo se
Ima li podataka kada će se najbolje videti sa ovih naših
prostora ?
zvezde.97nenad,
Večeras se kometa videla i iz Beograda golim okom. Uz poruku je
slika sa šemom gde treba tražiti kometu u prvoj polovini aprila,
ali prema onome što sam video lakše je uočiti nju nego zvezde i
sazvežđa na osnovu kojih je treba pronaći...
aprpm1.jpgzvezde.98nenad,
Uz poruku je crtež gde treba tražiti kometu krajem aprila i
početkom maja...
Hale-Bopp Weakened By the Moon
The glory of Comet Hale-Bopp suffers slightly due to a sky
significantly brightened by the Moon, which will be full on the
night of April 22nd. Reports indicate that the comet is still
near magnitude -0.5 with a dust tail visible to the unaided eye
and an ion tail visible in binoculars. Even in strong moonlight,
the comet will be unmistakable. Look at least 1Ż hours after
sunset when the sky is completely dark. Comet Hale-Bopp should be
obvious about 20° to 30° above the west-northwestern horizon
(depending on your latitude).
aprpm2.jpgzvezde.99nenad,
Zakonetka stara 30 godina je možda pred rešenjem - šta je uzrok
iznenadnim emisijama gama zraka u kosmosu? Skorašnja posmatranja
su ponudila neka moguća rešenja...
Gamma-Ray Bursters: Far or Near?
Astronomers may have come one step closer to solving a
30-year-old puzzle -- the nature and origin of gamma-ray bursts.
On February 28th a gamma-ray detector aboard the Italian-Dutch
spacecraft BeppoSAX was triggered, and the satellite's X-ray
cameras saw a simultaneous flash in the constellation Orion. That
alone was reason for interest.
But the news that followed has sent observatories worldwide into
a flurry of activity. In a March 12th IAU Circular, Paul J. Groot
(University of Amsterdam) and his colleagues announced that they
pointed the 4.2-meter William Herschel Telescope on La Palma to
the location of the X-ray hot spot and found an exceedingly faint
light source that then faded from view between March 1st and 8th.
Images from other observatories confirm the existence of what
appears to be a distant galaxy. This encourages scientists who
think gamma-ray bursts originate billions of light-years away.
However, another IAU Circular on April 17th reintroduced the
uncertainty. Patricia Caraveo (Institute of Cosmic Physics,
Milan) and her colleagues report that a pointlike object seen by
the Hubble Space Telescope in the same spot is moving across the
sky at a rate of a half arcsecond per year. This could mean that
the bursting gamma-ray source may be a relatively nearby object
within our own Milky Way. Establishing the distances to gamma-ray
bursters is crucial since that determines how much energy they
actually give off.
zvezde.100nenad,
Da li se ceo svemir okreće oko svoje ose? Možda će neki osnovni
zakoni morati opet da se menjaju, možda se svetlost ne kreće
svuda istom brzinom...
A New Spin on the Universe
Does the universe have something akin to a rotational axis? Two
astronomers suggest it might. They made the surprising finding by
studying radio observations of distant galaxies. In Monday's
issue of Physical Review Letters, John Ralston (University of
Kansas) and Borge Nodland (University of Rochester) report on how
radio signals in the cosmos seem to be polarized preferentially
in certain directions, suggesting that there is a universal axis.
If confirmed, this could have significant consequences for our
understanding of the universe. Ralston and Nodland explain that
the laws of electromagnetism may need revising, that the universe
didn't expand as uniformly as now thought, or that light in
intergalactic space may travel at different speeds for some
reason.
zvezde.101nenad,
Šema za gledanje Hale-Bopp komete u prvoj polovini maja.
maypm1.jpgzvezde.102nenad,
Nova planeta je otkrivena, istina ne u našem sistemu ali na svega
50-ak svetlosnih godina daleko.
Kruži oko Ro zvezde u sazvežđu Severna Kruna i verovatno je
veličine Jupitera. Astronomi kažeu da o životu na njoj nema ni
govora. Prema tome sledeće izbore definitivno treba dobiti. ;)
A New Extrasolar Planet
A team of eight astronomers has found evidence for a planet
around Rho Coronae Borealis, a 5th-magntiude star about 50
light-years away. Spectroscopic measurements made over 11 months
show that the star's velocity toward and away from Earth varies
by +/- 67 meters per second over a 40-day period. These values
argue for a companion at least as massive as Jupiter in an orbit
only about 40 million km in radius -- 1/4 of the Earth-Sun
distance.
Since Rho Cor Bor is a star much like our Sun, the suspected
planet would have a temperature of about 300° Celsius (more than
500° F) -- making it an unlikely habitat for life. The
companion's orbit is roughly circular, implying it formed at
roughly that location from gas and dust in the coalescing nebula
that created the star.
The observing team was led by Robert Noyes of the
Harvard-Smithsonian Center for Astrophysics.
zvezde.103nenad,
Po svemu sudeći ipak je dokazano postojanje malih (veličine kuće ;)
ledenih kometa koje konstantno padaju na Zemlju praveći rupe u
jonosferi. Ako se dokaz potvrdi i ako se ispostavi da su one u
tom istom ritmu padale na Zemlju od njenog postanka, to bi
značilo da večina vode na Zemlji potiče sa njih, a isto bi važilo
i za većinu organskih materija.
Return of the Minicomets
Spectacular images from an orbiting satellite show that the Earth
is being pelted more or less continuously by small comet-like
objects. The new views were released on May 28th by Louis A.
Frank (University of Iowa), whose camera on the Polar spacecraft
recorded the intruders as they sliced through the upper
atmosphere. Frank first called attention to these minicomets in
1986, based on their appearance in other spacecraft data. But his
idea was widely criticized because there was no other
observational evidence for the comets' existence (for example,
Apollo seismographs did not record them striking the Moon, nor
does the tenuous lunar atmosphere contain water).
However, the new Polar images have convinced many former
skeptics. Frank believes the interlopers have a mass of 20 to 40
tons and consist of almost pure ice. They begin to break up at
altitudes at least 10,000 kilometers above Earth, and their water
creates neutralized "holes" in the ionosphere that are seen by
Polar's cameras. The comets strike at rates of five to 30 per
minute. If this rate has been steady over billions of years, they
have contributed much of Earth's water and perhaps a large
proportion of its organic constituents.
For additional information and images, see Louis Frank's Web site
at the University of Iowa's Physics Department.
zvezde.104burazer,
Ovo poruku nisam znao gde drugde da stavim. U Beogradu se u
petak i subotu (20 i 21) odrzava BAV - Beogradski astronomski
vikend (Narodna opservatorija na Kalemegdanu), pa ko je
zainteresovan neka se oseca slobodnim i dodje.
PS Ulaz je slobodan. Ocekuje se velika guzva, a videcemo da li
ce je biti ;)))
zvezde.105nenad,
Astronomi se spore da li na mesečevim polarnim kapama ima vode
(leda) ili ne. Konačni odgovor će izgleda morati da sačeka kraj
godine kada će se "otići" na lice mesta.
A Dry Moon After All?
A new report, published in Science for June 6th, suggests that
there might not be any water at the lunar poles after all. Radar
echoes collected during the Clementine mission in April 1994
hinted that patches of ice might lie near the lunar south pole,
mixed with dust in the frigid floors of permanently shadowed
craters. But additional radar work with the 1,000-foot Arecibo
radio dish has dimmed that prospect.
Exploiting favorable Earth-Moon geometry in 1992, Nicholas J. S.
Stacy (Defense Science and Technology Organization, Australia),
Donald Campbell (Cornell University), and Peter Ford (MIT) used
Arecibo's radar beam to peer into the shadowed craters. The
presence of water ice would have changed the returning beam's
polarization in a telltale way, but that's not what happened. "We
don't see anything that suggests ice," says Campbell.
However, Clementine scientists are standing by their results. The
truth may be learned later this year, when a spacecraft called
Lunar Prospector returns to the Moon to conduct a sensitive
search for ice in the polar regions. If the Moon proves to be
bone dry, as the Arecibo data suggest, it would place stringent
constraints on the amount of water that could be delivered to the
lunar surface by infalling comets -- miniature or otherwise.
zvezde.106nenad,
Ulazak letelice Galilej u atmosferu Jupitera rezultirao je
neočekivanim ishodom - ali nova merenja pokazuju da gasoviti džin
ipak sadrži puno vode, a da je stiacaj okolnosti doveo do toga da
letelica prođe kroz jedan od malih i retkih delova gde vlage
nema.
Jupiter: Wet and Dry
Results from the Galileo spacecraft have restored scientists'
belief that the clouds of Jupiter contain water. This view had
been shaken when Galileo's probe found virtually no water during
its December 1995 descent into the clouds. However, Galileo's
near-infrared mapper has found some areas so humid that,
according to investigator Robert Carlson (Jet Propulsion
Laboratory), "it's either going to rain or it's raining right
now."
Apparently the probe chanced to enter the atmosphere in one of a
few very dry parcels, which together cover only about 2% to 5% of
the planet. These dry spots appear to be areas of downwelling
gas. "Winds rise from the deep atmosphere and lose water and
ammonia," explains Glenn Orton (JPL). "At the top, when they
converge and drop back down, nothing is left to condense into
clouds, and a dry clearing is created."
zvezde.107nenad,
Otkriveno je malo zvezdano jato koje će ili proći izuzetno blizu
nas ili je to već učinilo izazivajući meteorsku kišu koja je
mogla biti uzročnik nastanka života na zemlji. Ako se ispostavi
da nam se zvezde približavaju, ona najbliža će za "samo" milion
godina postati najbliža (samo 1 svetlosnu godinu) i gotovo
najsjajnija zvezda na nebu, magnitude 0,6.
Close-Call Star
Using newly released data from the European Space Agency's
Hipparcos satellite, a team of astronomers led by Joan
Garcia-Sanchez (JPL) has found a small handful stars that did or
will pass within 10 light-years of Earth. The closest future
approacher will be Gliese 710, now a 10th-magnitude red dwarf 63
light-years away in Ophiuchus.
About a million years from now this star will be only about a
light-year from the Sun and will shine at a brilliant magnitude
0.6. At that distance it may actually pass through the outer Oort
Cloud, sending a deadly shower of comets our way. Statistically,
over time other stars should have come as close or closer, and
the resulting infalls of distant comets may have triggered some
of the mass extinctions that have plagued life on our planet.
zvezde.108nenad,
Veliki tamni objekat otkriven je iza Neptuna...
King of the Kuiper Belt
A sizable body discovered last October in the Kuiper Belt beyond
Neptune has a unique orbit with links to the distant Oort Cloud
of comets. Designated 1996 TL66, this object is currently some 5
billion kilometers (35 astronomical units) from the Sun. Assuming
it has a dark surface, the new find is rather large and could be
up to 500 km across.
Discoverers Jane Luu (Harvard University) and her colleagues
calculate that 1996 TL66 is now close to the perihelion of a much
more eccentric orbit, one with a semimajor axis of 84 a.u. and a
period of nearly 800 years. No other known object bridges the
void between the Kuiper Belt and the far more distant Oort Cloud.
Whatever its origin, 1996 TL66 undoubtedly represents the first
of many such discoveries. Luu's group estimates that thousands
more bodies of comparable size and distance await discovery
within 30░ of the ecliptic plane.
zvezde.109johnnya,
>> Veliki tamni objekat otkriven je iza Neptuna...
Počelo-je-počelo... :)))
zvezde.110nenad,
Mesec nije jedini Zemljin satelit! A ako nas nešto bude zakačilo
to će biti ovo. ;)
Ispostavilo se da se jedan asteroid otkriven pre 10 godina kreće
po putanji koja je u direktnoj zavisnosti od putanje i položaja
Zemlje. Svakih 385 godina on je čas bliži čas dalji Suncu od
Zemlje - i to zbog njenog uticaja. U tekstu je dato objašnjenje
šta se tu dešava i kako sve to lepo funkcioniše, ali ja nešto
nisam siguran. ;)
Companion Asteroid
Two interesting asteroids are in the news this week. One of them
is unnamed but designated 3753. Discovered in 1986, this
5-kilometer-wide body has an inclined and eccentric path that
crosses the orbits of both the Earth and Venus. Simulations by
Paul Wiegert (York University) and two colleagues show that 3753
circles the Sun in what's termed a horseshoe orbit with respect
to Earth.
It works like this: the asteroid circles the Sun in just a bit
under 1 year. Over time this slight mismatch allows it to
overtake Earth, every 385 years to be exact. But as it comes
nearby the Earth's gravity adds a little energy, expanding the
asteroid's orbit. Suddenly circling the Sun in just over 1 year,
the asteroid never quite catches Earth and moves away. Then, 385
years later, Earth catches up, this time robs 3753 of a little
energy, and drops it into a smaller, faster orbit.
This asteroid appears to be a companion of sorts, under Earth's
control. The only other known example of such horseshoe orbits
involve Janus and Epimetheus, two small satellites of Saturn
located just beyond that planet's ring system. Sometime within
the next 100 million years, however, asteroid 3753 will escape
its captivity, either crashing onto one of the inner planets or
being flung away onto a totally new path.
zvezde.111nenad,
Izgleda da "mala planeta" (asteroid) Dionis ima svoj satelit!
Astronomi se nadaju da će otkriti nešto više tokom jula kada je
on u okultaciji pošto će sledeća prilika biti tek kroz 13 godina.
Doubled Dionysus?
The second newsy asteroid is 3671 Dionysus, an Earth-crosser in a
3.25-year orbit. When astronomers Stefano Mottola and Gerhard
Hahn (German Aerospace Research, Berlin) observed its rotational
light curve earlier this month, they noticed that every 1.15 days
the asteroid's brightness would suddenly drop by 0.08 magnitude.
But the asteroid itself is known to rotate every 2.7 hours. So
they've concluded that Dionysus probably has a satellite, and
we're looking right along its orbital plane. If they're right,
every 28 hours this little moon either passes in front of or
behind the main asteroid.
Mottola and Hahn point out that Dionysus will come within about
17 million km of Earth in early July, when it will brighten to
15th magnitude. Astronomers around the world are trying to learn
more in the coming weeks, as the asteroid won't be near us again
for 13 years.
zvezde.112zormi,
* Mesec nije jedini Zemljin satelit! A ako nas nešto bude zakačilo
* to će biti ovo. ;)
Taj asteriod ima "inklinisanu" orbitu i nema šanse da se sudari sa Zemljom.
zvezde.113vdjole,
> Po svemu sudeći ipak je dokazano postojanje malih (veličine kuće ;)
> ledenih kometa koje konstantno padaju na Zemlju praveći rupe u
> jonosferi.
> Frank believes the interlopers have a mass of 20 to 40
> tons and consist of almost pure ice.
> The comets strike at rates of five to 30 per
> minute.
Da nije ovde negde ipak neki lapsus sa redovima veličine za neki od
podataka. Objekti "veličine kuće" sastavljeni od leda a koji padaju
svakih nekoliko sekundi bi verovatno odavno bili primećeni radarima
onih službi što se brinu o lokacijama raznoraznog đubreta u orbiti
(koliko znam led dobro reflektuje takve radio talase). Sigurno bi
bili vidljivi i golim okom- uostalom i svaki satelit pristojnije
veličine se pod povoljnim uslovima vidi golim okom. Pošto taj
hipotetički led sigurno ne bi bio baš čist već bi sadržao i prašinu i
slično, verovatno bi pri padu svakog ovakvog objekta nastao i prilično
impresivan vatromet. Mrzi me da računam, ali verovatno bi sa takvom
učestanosti i veličinom objekata sudar sa onolikim satelitima i drugim
kosmičkim letelicama što se vrte unaokolo bio sasvim realna mogućnost.
zvezde.114nenad,
Veliki problemi za orbitalnu stanicu Mir i dalje traju...
The Russian space station Mir's problems could be just
beginning after an unmanned cargo craft crashed into a
crucial module, wiping out half the station's power, space
experts said.
"It's a complicated situation and it's going to take a lot
of work to recover," Jerry Linenger, Mir's previous NASA
resident, told a news conference Wednesday.
The Progress cargo craft, which went out of control during
a docking exercise Wednesday, ploughed into the station's
Spektr module, causing a loss of air pressure and wrecking
a solar panel.
The power from the module's four electricity-generating
solar panels was cut off when the crew shut the hatch to
seal off the damaged, leaking compartment. Batteries used
to power the station during the orbital night were also
lost.
The power loss is likely to have a snowball effect on other
Mir systems and will make life difficult for the three-man
crew, which includes British born NASA astronaut Michael
Foale. They have already closed down some life-support
systems to conserve energy.
"It will be a darkened ship," Linenger said. "(They will
have to be) very careful before switching anything on."
The power loss could lead to rising carbon dioxide levels
in the breathing air, so the crew will have to avoid
exerting themselves, he added. Exercise, crucial for space
travellers to ward off the delibitating effects of
weightlessness, would have to be suspended.
"The power is the main concern because you depend on that
to keep your life support systems going and for the whole
operation of the station," Linenger said.
It may be possible for spacewalking astronauts to reroute
electrical cables from the crippled module's solar panels
to regain some of the station's lost power, said Frank
Culbertson, who heads NASA's joint program with the Mir
space station.
"The Russians have a very good record in trouble-shooting
problems in orbit," Philip Clark, editor of Jane's Space
Directory, said. "In 1985, they brought the Salyut 7
station back from the dead."
Just abandoning the Mir space station would not be an easy
option, Clark said. The 130-140 tonne complex is too large
for a safe reentry that would dump the space station into
an ocean.
Abandoned in space, Mir would probably fall to earth in
four to five years. Its orbit takes it across most of the
world's populated areas, in a band roughly south of London
and north of Cape Horn at the tip of Argentina.
Russian space officials have admitted they do not know what
to do with the station when its useful life ends.
The U.S. space shuttle might be able to help safely dispose
of Mir before parts of it end up on the White House lawn,
said Clark.
"There will be incentive for NASA to help once they realise
it could rain debris on Pennsylvania Avenue," he said.
Russia's Salyut 7 space station, a fifth of the size of
Mir, rained debris on South America when it reentered in
1991, but there were no reports of damage or injuries.
Russia had hoped to operate the station until the planned
international space station begins operations in early
1999.
zvezde.115nenad,
> Da nije ovde negde ipak neki lapsus sa redovima veličine za neki od
> podataka.
Zaista ne znam, vesti preuzimam iz proverenih izvora tako da ne
bi trebalo da su u pitanju naklapanja već rezultati nekakvih
(kakvih-takvih) naučnih istraživanja.
> Objekti "veličine kuće" sastavljeni od leda a koji padaju
> svakih nekoliko sekundi bi verovatno odavno bili primećeni radarima
> onih službi što se brinu o lokacijama raznoraznog đubreta u orbiti
> (koliko znam led dobro reflektuje takve radio talase).
Hm... Za led zaista ne znam kako reaguje na radio talase, ali da
se njegova interakcija sa vazduhom ipak ne dešava malo previsoko
za radare? Ja se sećam nekih zvaničnih podataka i statistika o
količini materije koja svakog minuta/dana padne na zemlju, možda
se ovde samo radi i preciznijem određivanju sastava te materije?
> Sigurno bi
> bili vidljivi i golim okom- uostalom i svaki satelit pristojnije
> veličine se pod povoljnim uslovima vidi golim okom.
Ako van grada gledaš u noćno nebo uglavnom ne prođe 5-10 minuta
između "zvezda padalica" koje se vide gore. To su, naravno,
meteori, a možda je se baš radi o ovim ledenim?
U svim tim meteoritima što dosegnu zemlju je, svakako, vodu
najteže otkriti jer ako nešto i stugne do zemlje, ona sigurno
ispari.
zvezde.116nenad,
Najveća do sada zabeležena vulkanska erupcija... na Jupiterovom
mesecu Io. :)
Pele's Plume
A newly released image from the Hubble Space Telescope shows the
Jovian moon Io spouting off as never before. Last July HST
captured a major eruption of Pele, one of Io's most powerful
volcanoes. A sulfur-driven plume of gas and dust extended 400
kilometers into space, even higher than when seen during Voyager
1's flyby in 1979. For the plume to attain so great a height,
John Spencer (Lowell Observatory) calculates that the material
had to be escaping at nearly 1 km per second. Pele's spoutings
are so big in part due to Io's low gravity and lack of a dense
atmosphere, and in part because they are simply more energetic
than volcanic eruptions here on Earth.
zvezde.117nenad,
Prvi nalazi koji bi mogli da potvrde Ajnštajnovu pretpostavku da
crne rupe "rotiraju".
A New Spin on Black Holes
In the June 20th issue of Astrophysical Journal Letters, Shuang
Nan Zhang (NASA/Marshall) and others report that two black holes
they've been studying with spacecraft are spinning 100,000 times
per second. They deduced this by accurately determining the
closest stable orbit to a given black hole, which depends on the
latter's spin rate. Zhang notes that this knowledge will be
enormously helpful in determining how much angular momentum a
black hole has "swallowed" during its lifetime. The observations
also confirm Einstein's prediction that black holes do spin.
zvezde.118pdeze,
Pozdrav!
Citajuci relativno novu knjigu Arthur C. Clarke-a:
The Hammer of God (1993), nais'o sam na poglavlje
u kojem se radi o Jupiterovim Trojancima, asteroidima
koji se nalaze na Jupiterovoj orbiti 60 stepeni ispred i
iza njega i koji se nalaze u nekom ekvilibrijumu
sila Sunca i Jupitera...
E sad, ja o tome (pre ovog) nisam cuo nista, pa ne mogu
razluciti da li je to nauka ili fantastika (odlican ovaj Klark ;))
Pa ako Trojanci postoje, interesuju me koje su tu sve sile
prisutne (osim gravitacije) koje 'drze' te asteroide u
istom mestu.
P.S. Naslov knjige sam napisao na engleskom posto nemam pojma
kako je kod nas prevedeno
zvezde.119petarg,
>Trojanci
Ekvilibrijum je ravnoteza.
Trojanci postoje, i evo njihovog opisa iz knjige
'University Astronomy', koju s napisali Pasachoff i
Kunter.
JG
trojan.txtzvezde.120nenad,
> Pa ako Trojanci postoje, interesuju me koje su tu sve sile
> prisutne (osim gravitacije) koje 'drze' te asteroide u
> istom mestu.
Trojanci postoje i jesu asteroidi (male planete), ali njihovo
kretanje nije u direktnoj vezi sa Jupiterom. Jedina veza i
interesantna stvar su njihove povremene okultacije sa njim.
zvezde.122vdjole,
>Trojanci postoje i jesu asteroidi (male planete), ali njihovo
> kretanje nije u direktnoj vezi sa Jupiterom. Jedina veza i
> interesantna stvar su njihove povremene okultacije sa njim.
Pa ako su u Lagranževim tačkama, kao što kaže u onom fajlu uz
prethodnu poruku, onda valjda JESU u (gravitacionoj) vezi sa
celinom Jupiter-Sunce. A ako slede/prethode Jupiter za 60 stepeni
po orbiti oko Sunca, kako onda može on da ih zakloni?
zvezde.123vdjole,
> Pa ako Trojanci postoje, interesuju me
U fajlu uz poruku 7.119 je lepo objašnjeno. Možda bi neko kome je to
struka mogao malo opširnije da napiše nešto o Lagranževim tačkama-
to je jedan od kurioziteta zakona nebeske mehanike i zasniva se na
gravitacionim silama i položaju centra masa. Koliko je meni
poznato, sistem od dva tela ima 5 Lagranževih tačaka - mesta koje
predstavljaju stabilnu lokaciju za neki treći objekat. Često se opisuju
na sistamu Zemlja-Mesec:
Prva tačka je između Zemlje i Meseca, što bi se (malo neprecizno) reklo,
tamo gde su njihova gravitaciona privlačenja jednaka (ako ste čitali "Put
oko Meseca" Žila Verna kada ste bili mali...).
Druga tačka je na pravoj koja prolazi kroz Zemlju i Mesec, ali IZA
Meseca (tj. stalno na suprotnoj strani Meseca od Zemlje).
Treća tačka je na istoj pravoj, ali stalno sa suprotne strane Zemlje
u odnosu na Mesec.
Četvrta i peta tačka se nalaze "levo i desno" od sistema Zemlja-Mesec
(kao što su Trojanci "levo i desno" od sistema Sunce-Jupiter) i
interesantno je da stabilne lokacije nisu u samim tačkama nego na nekim
"pasuljoidnim" putanjama opisanim oko tih tačaka.
Elem, ovo napisah koliko se sećam nečega što sam mnogo davno čitao, pa
ako neko može to lepo da objasni...
zvezde.124nenad,
> A ako slede/prethode Jupiter za 60 stepeni
> po orbiti oko Sunca, kako onda može on da ih zakloni?
Onda sam ja nešto pomešao, tj. njih sam pomešao sa nekim drugim
asteroridima. :)
zvezde.125rdejan,
MARS
IN ITS FIRST FULL WEEK, PATHFINDER DELIVERS
CUTE NICKNAMES, MONSTER PANS AND AN
EXTRATERRESTRIAL CRASH
BY LEON JAROFF
Barnacle Bill. Yogi. Casper. Scooby Doo. Flat Top, Boo-Boo. The
Couch. Souffle. After billions of years of anonymity, a motley
collection of rocks on the Martian flood plain called Ares
Vallis at last had names of their own. And back on Earth last
week, the Pathfinder scientists who had playfully nicknamed the
rocks were enjoying, as one of them phrased it, "a rock
festival," reveling in the torrent of data being yielded by the
rock stars and their surroundings.
Indeed, after only a week on the surface of Mars, Pathfinder had
conducted dozens of worthy science experiments, had begun to
challenge at least one long-held perception about the red planet
and had transmitted more than 1,700 photos of the landscape,
many of which were incorporated into a "monster pan," a
spectacular 360[degrees], three-dimensional, horizon-to-horizon
mosaic image that, when viewed through 3-D glasses, is almost as
good as being there. The mission had also achieved a historic
first on Mars: a motor-vehicle accident.
The undisputed star of the week, however, surpassing even the
rocks, was the 25-lb. Sojourner, which Rob Manning, Pathfinder's
flight-systems chief engineer, dubbed "The Little Rover That
Could." Having inched its way down the steeply inclined lander
ramp, the six-wheeled Sojourner crept gingerly onto the Martian
surface early last week and, in its first official scientific
experiment, shoved the nose of its X-ray spectrometer into the
dust at the foot of the lander.
After bombarding the reddish dirt with helium nuclei and
analyzing the resulting patterns of radiation, the spectrometer
revealed that the soil was rich in iron and virtually identical
to that examined at other sites 21 years earlier by the Viking
landers. This suggested to scientists that Martian topsoil is
widely distributed by the planet's frequent global dust storms.
Why the reddish hue? "The surface of Mars is rusting," explains
Jim Bell, a Cornell University scientist.
Sojourner next turned toward Barnacle Bill, a 10-in.-high rock
lying within arm's length of the lander, and closed in to sniff
out its mineral content. Displaying a picture of the rover at
the rock, the ever buoyant project scientist Matthew Golombek
joked, "Here we have proof that Sojourner sort of nestled up and
kissed Barnacle Bill." The high-tech buss, profferred by the
rover's X-ray spectrometer, produced an unexpected finding: the
rock was apparently loaded with silicon or silicon dioxide,
commonly known as quartz.
What surprised many scientists was that the data appeared to
liken Barnacle Bill to andesites, which are volcanic rocks
usually found on Earth in the Andes Mountains and other areas of
explosive volcanism. Andesites are typically formed by the
repeated melting, solidifying and remelting that occurs during
the tectonic-plate processes that shape and reshape terrestrial
continents. Yet Mars seems to have very few volcanoes and shows
no signs of tectonic plates, which suggested to some scientists
that the planet wasn't internally active long enough to form
andesites. Then what process could have created Barnacle Bill?
"How that happens in the absence of plate tectonics is not well
understood," admits Robert Strom, a University of Arizona
planetary scientist. To NASA Goddard scientist Jim Garvin, the
finding suggests that a geology significantly more complex than
scientists had expected was at work on Mars. "It's not the
easiest rock to make," he says, "and that alone is very
exciting."
Sojourner also managed to obtain a "fingerprint" of the other
chemicals in Barnacle Bill. The fingerprint turned out to be
virtually identical to those of the 12 meteorites found on Earth
that are believed to have Martian origins. "So," concluded
University of Tennessee scientist Hap McSween after the visit to
Barnacle Bill, "now we can say that we have analyzed 13 Martian
rocks."
Moving on, Sojourner headed toward a nearby, bear-shaped rock
named Yogi, stopping on the way to test the consistency of the
soil by using five of its wheels for traction and one to dig
into the dirt. Sojourner's cameras showed that the rover's shove
had displaced what seemed to be a thin layer of crust over the
soil. "We used the rover as sort of a bulldozer," explained
Golombek.
Then, demonstrating a technique that any driver maneuvering into
a tight parking spot would envy, Sojourner energetically
swiveled its wheels back and forth and "crabbed" sideways into a
position near Yogi. The next day, however, when the rover moved
toward the rock to perform X-ray spectroscopy, says project
scientist Justin Maki, "it got a little too enthusiastic." What
really happened is that Sojourner's controllers at NASA's Jet
Propulsion Laboratory failed to take into account a small
outcropping at the base of the rock. Pushed ever so slightly
upward, the rover gently bumped into the rock and began trying
to climb it. As one of the rover wheels began rolling up the
side of Yogi, sensors aboard Sojourner detected a tilt and shut
down the little vehicle, leaving it hung up, in effect, on the
rock.
A low groan swept across the operations room at the J.P.L., and
pictures transmitted by the lander soon afterward showed
Sojourner askew, leaning against Yogi and seemingly helpless.
But a quick check of the rover's systems confirmed that it was
in good health, and controllers had little doubt that they could
restart Sojourner, back it off the rock and try a better
approach.
No such luck. On Sol 6, NASA's designation for Pathfinder's
sixth day on Mars, they transmitted the appropriate instructions
to the lander, which was to relay them to Sojourner. But the
Pathfinder team had inexplicably failed to awaken the lander,
which is shut down every Martian night, and the message was not
received. "One miscalculation cost us the whole evening," sighed
J.P.L. deputy project manager Brian Muirhead. As a result,
Sojourner remained incapacitated and unable to operate the next
day. That led a rover team member to crack, "On the seventh day,
it decided to rest."
NASA has ambitious plans for Sojourner this week. It wants the
rover to investigate Scooby Doo and Casper, two rocks that look
intriguingly white in lander photos and just might contain hints
of ancient Martian life. How so? To scientists, the duo's
whitish hues suggest that they may be sedimentary rocks. "That
would be awesome," says Ken Edgett, an Arizona State University
geologist, "because sedimentary rock is the kind of thing that
forms under water. And when you have water that sits around for
a long time and sediments pour into it, the possibility of
preserving fossils goes up."
Pathfinder's lander too should have a busy week. It is scheduled
to shoot pictures of the Martian sunrise and sunset, the moons
Deimos and Phobos and other features of the landscape.
Still, J.P.L. engineer Randii Wessen has some concerns. "We're
living on borrowed time," he says. Sojourner has a 100% chance
of surviving for seven days, he explains, "because that's what
we designed it for. But after that, maybe it's got a 90% chance
for eight days or 75% for two weeks." While the rover's
electronics are protected in a warm box, the Martian
temperatures, swinging wildly from 8[degrees]F to 130[degrees]F,
may degrade the batteries. "We'll have to see how well they hold
charges," says Wessen. Another threat, both to the lander--which
is designed to survive for 30 days--and to the rover is Martian
dust, which could coat the solar panels, affecting their ability
to provide recharging current.
Yet at week's end the lander batteries were recharging smartly,
and Pathfinder mission manager Richard Cook seemed unconcerned
about Sojourner's fast-expiring design life. "I think at this
point we're all expecting it to live for a long time," he said.
"It has proved to be very capable."
And Cook was proved right. On the morning of Sol 8, Sojourner
awoke, received its instructions and, after one more brief
glitch, backed off Yogi, approached again and began eagerly
sniffing out the rock's chemistry. Back at J.P.L., the exuberant
Pathfinder team was predicting that Sojourner might live for
weeks--and even months. Indeed, the little rover just could.
--Reported by Dan Cray/Pasadena and Dick Thompson/Washington
PS. Nije za online ;)
Pozdrav, Dejan
zvezde.126nenad,
Jednim od najznačajnih dostignuća u astronomiji ove godine smatra
se povezivanje emisija gama zračenja sa vidljivim događajima. To
do sada nije uspevalo, povremene emisije su detektovane a da se
ništa nije znalo o njima, njihovom poreklu i prirodi.
Međutim, možda ipak i dalje ne znamo mnogo - nijedna od
propratnih pojava se nije desila _tačno_ na mestu gde su
detektovani gama zraci. Something is outhere... ;)
Another GRB Counterpart?
One of the most significant developments in astronomy this year
has been the association of visible objects with gamma-ray
bursters. For three decades frustrated astronomers have observed
random flashes of high-energy radiation from all over the sky
with hardly any clues as to their origin. Typical events last
only seconds or minutes, and they never repeat. No matter how
hard they tried, researchers couldn't find anything visible at
the positions of any of the thousands of gamma-ray bursts
observed over the years.
Success finally came when an orbiting X-ray telescope and several
ground-based optical giants spotted counterparts to a gamma-ray
burst on February 28th, then another on May 8th. Now a third
optical counterpart appears to have been detected, this time
following an intense event picked up last month by NASA's Compton
Gamma Ray Observatory and several other satellites.
The burst erupted in Cetus on June 16th and was over in less than
3Ż minutes. Four hours later, after the burst's position was
nailed down to within a few arcminutes, NASA's Rossi X-ray Timing
Explorer examined the area and detected an X-ray afterglow.
Within a few days Japan's Advanced Satellite for Cosmology and
Astrophysics found several variable X-ray sources in the
vicinity, and the Keck II 10-meter telescope revealed a
visible-light object fading from view.
Curiously, none of these sources exactly match each other's
position, and none lie squarely at the coordinates of the
original gamma-ray burst. So perhaps none of these variables has
anything to do with the burst after all! As astronomer A. Udalski
(Warsaw University) put it on IAU Circular 6690, "Apparently the
background of variable objects is high, and it may contribute
significantly to false afterglow detections."
zvezde.127nenad,
Evo prilike da zaradite 500 dolara - otkrijte asteroid čija se
orbita ukršta sa Zemljinom. ;) Prvih 10 koji to urade dobijaju
nagradu, a jedan asteroid je već otkriven.
Benson Prize: 1 Down, 9 to Go
Speaking of asteroids, three weeks ago James Benson of Space
Development Corporation announced that he would award $500 to the
first 10 amateur astronomers who discover minor planets whose
orbits cross Earth's.
And already we have a winner! Roy Tucker of Tucson, Arizona,
picked up a fast-moving object in a sequence of CCD images made
on the evenings of June 28th and 29th with his Celestron 14-inch
telescope. Follow-up observations made over the next few nights
by astronomers worldwide confirmed the 18th-magnitude blip to be
a previously unknown minor planet. Designated 1997 MW1, it orbits
the Sun every 0.91 year in an elongated path that brings it
inside the orbits of the Earth and Venus. It is thus an Aten-type
asteroid, only the 25th such object known.
The Benson Prize was established to encourage amateurs to help
locate the hundreds of Earth-crossers believed to inhabit the
inner solar system. Space Development Corporation hopes to mine
these asteroids for natural resources.
zvezde.128castrvm,
Koga zanima moze upravo da pogleda zamracenje
meseca .
zvezde.130vstan,
- novo -
windows/misc/*.*
================
skymap.exe 1877k ű Skymap 3.1.11: odlican astronomski program (Win95/NT)
zvezde.131supers,
Na adresi http://ni.ac.yu/Prez/gid/izdanja/sunce/start.htm
nalazi se kompletna Web verzija knjige Kako posmatrati Sunce
Zorana Tanasijevića. Ova publikacija je vodič za teleskopsko
i vizuelno posmatranje Sunca, fotografisanje i obradu podataka.
Prezentacija obiluje slikama, od kojih su dobar deo animirani gifovi.
Brižljivo je optimizovana da se može lako gledati i na 14400bps.
Ima i malo JavaScripta, CP1250, best viewed with Netscape.
Imao sam čast da učestvujem u izradi prezentacije :)
zvezde.132stameni,
Na jugozapadnom delu neba se negde od 17:00 do 18:30 može
videti jedan prilično sjajan objekat, koji je najverovatnije neka
planeta, jer ne treperi i nije potpuno beo. Prema Skyglobeu, u to
vreme se tamo nalaze Venera i Mars, ugaono jako blizu, pa je teško
odrediti šta je to zapravo. Uz to, vidi se samo jedno telo.
Ako neko ima efemeride za ovu godinu, ne bilo mu teško da
pogleda da li u ovo kalendarsko doba manju magnitudu (odnosno
magnitudu "više u minus") ima Mars ili Venera, da vidimo šta bi to
moglo da bude.
Inače, još od leta se na jugu uveče može videti Jupiter -- sada
malo zapadnije.
zvezde.133zormi,
* Na jugozapadnom delu neba se negde od 17:00 do 18:30 može
* videti jedan prilično sjajan objekat, koji je najverovatnije neka
* planeta, jer ne treperi i nije potpuno beo. Prema Skyglobeu, u to
* vreme se tamo nalaze Venera i Mars, ugaono jako blizu
Venera najverovatnije. Mars je crvenkast i mnogo manje sjajan.
zvezde.134nbjvsb,
>> * Na jugozapadnom delu neba se negde od 17:00 do 18:30 moze
>> * videti jedan prilicno sjajan objekat, koji je najverovatnije neka
>> * planeta, jer ne treperi i nije potpuno beo. Prema Skyglobeu, u to
>> * vreme se tamo nalaze Venera i Mars, ugaono jako blizu
>>
>> Venera najverovatnije. Mars je crvenkast i mnogo manje sjajan.
Venera je, 100%. Akcenat na 'prilicno sjajan objekat'.
Mars je, vizuelno, reda velicine sjajnije zvezde, pa ga je ponekad tesko
prepoznati (ukoliko ne poznajes nebo dovoljno dobro), narocito ako je nisko
nad horizontom kada treperi zbog zagadjenja, isparenja, i slicnih stvarcica
iz atmosfere, dok je Venera prilicno raspoznatljiva (najsjajniji objekat na
nebu posle Sunca i Meseca).
zvezde.135nenad,
Novootkrivena najveća zvezda u našoj galaksiji. Do sada nije bila
otkrivena jer se nalazi iza gustog oblaka prašine. Dvesta puta
teža od sunca i zrači 10 miliona puta veću energiju. Ali, neće
još dugo...
Most Luminous Star
There's apparently a new stellar heavyweight champion in the
galaxy. It lies 25,000 light-years away in Sagittarius and is
hidden from view by dense clouds of dust. The star was first
spotted in infrared observations several years ago, but in 1995
astronomer Don Figer suggested that the star also created the
surrounding cloud of glowing gas, which has been dubbed the
Pistol Nebula.
Figer has followed up with observations using the Hubble Space
Telescope's recently installed Near-Infrared Camera and
Multi-Object Spectrometer. The star -- which apparently emits 10
million times as much energy as the Sun -- may be only 1 to 3
million years old, and it will live for only another 1 to 3
million years before exploding in a supernova.
While it initially may have been some 200 times the mass of the
Sun, it is actively throwing off tremendous amounts of matter and
so is not that massive now. The UCLA researcher and his team
presented Hubble's view of the region this week, clearly showing
material that Figer estimates was ejected 4,000 and 6,000 years
ago.
zvezde.136nenad,
Sve planete Sučevog sistema sem Plutona biće moguće videti
istovremeno na nebu krajem novembra i početkom decembra. To se
naravno mora desiti uveče ili ujutru (ovoga puta uveče), što
znači da se mora posmatrati van grada. Tu negde će biti i mesec,
detaljnije u tekstu koji sledi i slici uz poruku...
Planet Parade
If you get an early start in the evening, you can make a sweep of
nearly all of the solar system's major planets. Venus through
Neptune are well up as the sky darkens with evening twilight,
while Mercury is gradually climbing above the southwestern
horizon, approaching its greatest elongation from the Sun at the
end of November. Starting from Mercury and heading east, you'll
find Mars, Venus, Neptune, Uranus, Jupiter, and Saturn. Only
13th-magnitude Pluto is largely out of reach, as it is quite low
above the west-southwest horizon.
v971201.jpgzvezde.137nmaricic,
Voleo bih da konstruisem teleskop, pa ako neko ima korisnih saveta
neka mi se javi. Nebojsa ű Maricic
zvezde.138vdjole,
>Voleo bih da konstruisem teleskop,
Vrlo široko navedena želja. Koliki, kakav, pošto?
zvezde.139nmaricic,
Kakav teleskop? Za posmatranje Meseca, Saturnovih prstena, pruga na
Jupiteru...
Posedujem uputstvo za konstrukciju Njutnovog alt-azimutnog
reflektorskog teleskopa 120/90, ali ono mi nije od velike pomoci.
┐╗ Uzgred, da li Astronomsko drustvo Rudjer Boskovic ima EMail?
zvezde.140naumov,
ima
zvezde.141pifat,
>>┐╗Uzgred, da li Astronomsko drustvo Rudjer Boskovic ima EMail?
astrorbo@eunet.yu
Prezentacija je na //solair.eunet.yu/~astrorbo
zvezde.142pdeze,
Pozdrav!
Nedavno sam poceo da se bavim posmatranjem promenljivih zvezda,
posto sam se tek sad dokopao durbina sa precnikom od 8cm (4 godine
mi je trebalo da objasnim direktoru gimnazije da sam ja nevidjeni
potencijal za astronomiju ;)
Trazim amatere, koji se aktivno bave promenljivima radi razmenjivanja
iskustava i rezultata, tek da udjem u fazon.
Oskar
zvezde.145sherloc,
Zeleo bih da kupim teleskop, ali ne znam gde to ima da se kupi,
pa ako neko zna bio bih zahvalan na informaciji.
Citao sam ranije poruke, i primetio da se uglavnom govori da nema
nigde ovde da se kupi, vec samo u inostranstvu, ali reko ko zna
mozda se desilo nesto novo...
Toliko.
zvezde.147pdeze,
Pozdrav!
Surfujem ja tako webom i naidjem na strava programcic na sajtu NASA-e.
Toliko je dobar da nisam mogao odoleti da ga ne posaljem.
LM, radi se o sajtu sa java appletom, koji prikazuje trenutni polozaj
nekih satelita na orbiti projektovano na kartu sveta !!!
To ukljucuje Mir, Hubble Space Telescope,
UARS, COBE i GRO. Za ove nisam siguran, al' znam sta je Mir i HST ;)
U zip su ubaceni svi fajlovi sa sajta koji su potrebni za applet (neke
klase i tako to).
A sta se tice kopirajta (dragi moderatori), sve je legalno (pitao
sam).
DL, pa recite kako vam se svidja!
Ako vas interesuje skinuo sam jos i neki JPass, koji izracunava za
nekih tridesetak satelita kada ce moci da se vide na nasem nebu,
sa sve ucrtanim pravcem prolaska na zvezdano nebo !!!
Sve ovo mozete naci i ovde:
http://liftoff.msfc.nasa.gov/RealTime/Jtrack/Spacecraft.html
jtracj.zipzvezde.148pvlada,
> Ako vas interesuje skinuo sam jos i neki JPass, koji izracunava za
Naravno, interesuje ;)
Pozdrav Vlada
zvezde.149pdeze,
>> Ako vas interesuje skinuo sam jos i neki JPass, koji izracunava za
>
> Naravno, interesuje ;)
Sorry, zakasnio si.
Ostao sam bez modema od 14400, pa sad koristim
jedan na 2400 :(((, tako da ne mogu poslati taj fajl.
U svakom slucaju za one sa nalogom za inet, stvar
(JPass) se nalazi na adresi:
http://liftoff.msfc.nasa.gov/RealTime/JPass/JPass.html
CU,
Oskar