Thursday, January 12, 2012

Milky Way has billions of habitable planets! / Mlečni put ima milijarde naseljivih planeta!

            After a six-year star survey astronomers came to the conclusion that habitable planets may be in orbit around billions of stars in the Milky Way. This suggests that planets on which humans could live are commonplace in our galaxy. Habitable zone means conditions are not too cold and not too hot but “just right” to allow surface liquid water and, potentially, life.
            However, just because a planet has conditions suitable for life, it does not follow that life has evolved there. Life as we know it on Earth had developed as a result of “many unique events”.
            Most news of exoplanets in recent years has come from the Kepler telescope. Kepler finds planets using a technique known as the transit method. It watches for tiny dips in a star's brightness caused when a planet crosses the face of, or transits, the star, blocking some of its light.
            The Kepler team has discovered the three smallest alien planets yet, including one that's just the size of Mars. These three planets orbit a red dwarf star known as KOI-961, which is just one-sixth the size of our sun and is located 120 light-years away, in the Constellation Cygnus (The Swan).
            This is the tiniest solar system found so far that it’s actually more similar to Jupiter and its moons in scale than any other planetary system. The discovery is further proof of the diversity of planetary systems in our galaxy.
            The three planets orbit very close to their star which makes them too hot to be in the habitable zone. They are thought to be rocky like Earth.
            Finding a Mars-sized planet is a big step forward because it is already hard to find something the size of the Earth.
            Red dwarfs are the most common kind of star in the Milky Way. The discovery of three rocky planets around one red dwarf suggests that our galaxy might be teeming with similar worlds.
            The three tiny exoplanets add to an impressive list of recent discoveries by Kepler. Last month, astronomers announced the discovery of the first two Earth-size alien planets, as well as one slightly larger than our home planet that resides in its star's habitable zone. To date, Kepler has found about 35 alien planets, but also an additional 2,300 exoplanet candidates that await confirmation by follow-up studies. Kepler scientists have estimated that at least 80 percent of these potential planets will end up being the real deal.

CREDIT: NASA/JPL-Caltech

             Posle šestogodišnjeg istraživanja, astronomi su došli do zaključka da bi u Mlečnom putu moglo da bude više milijardi potencijalno naseljivih planeta! To znači da one nisu izuzetak, već uobičajena pojava u našoj galaksiji. Da bi neka planeta bila potencijalno naseljiva, temperatura na njoj ne bi smela da bude suviše visoka, niti suviše niska, već „tačno takva da omogući“ uslove postojanja tečne vode na površini, a možda i neki oblik života.
            No, ukoliko neka planeta i ima uslove pogodne za život, to ne znači da su se oni automatski i razvili. Život, kakav poznajemo na Zemlji, nastao je kao rezultat “mnoštva jedinstvenih događaja”.
            Za većinu ovih najnovijih otkrića planeta, zaslužan je teleskop Kepler. On otkriva planete koristeći tehniku koja je poznata kao tranzitni metod - prati male promene do kojih dolazi kada planete prolaze pored zvezda, blokirajući njihovu svetlost.
            Najnovije otkriće Kepler tima je objavljeno 11. januara ove godine, a odnosi se na otkrivanje najmanjih planeta do sada, od kojih je jedna gotovo iste veličine kao planeta Mars. One kruže oko crvenog patuljka (mala i relativno hladna zvezda) poznatijim pod nazivom KOI-961, koji ima jednu šestinu mase našeg Sunca i nalazi se u sazvežđu Labud, udaljenom 120 svetlosnih godina.
            Ovo je najmanji solarni sistem koji je otkriven do sada i više podseća na planetu Jupiter sa svojim satelitima, nego na planetarni sistem. Otkriće predstavlja još jedan dokaz koliko je raznovrstan planetarni sistem u našoj galaksiji.
            Tri novootkrivene planete kruže veoma blizu svog sunca pa je temperatura na njima veoma visoka. Naučnici veruju da su stenovite poput naše Zemlje.
            Pronalazak planete koja je velika kao Mars, veliki je korak napred jer je do sada bilo teško otkriti i planete velike kao Zemlja.
            Crveni patuljci su najčešća vrsta zvezda u Mlečnom putu. Otkriće ove tri planete oko jedne od njih sugeriše da bi naša galaksija mogla da vrvi od sličnih svetova.
            Teleskop Kepler već ima impresivnu listu otkrića, ovo su samo najnovija. Prošlog meseca astronomi su objavili otkriće prve dve planete koje su gotovo iste veličine kao Zemlja, kao i otkriće još jedne, nešto veće. Kepler je do danas pronašao više od 35 planeta, ali i još 2 300 nebeskih tela koja čekaju da budu potvrđena kao planete kroz detaljnija proučavanja. Naučnici procenjuju da će najmanje 80 odsto od tih 2 300 potencijalnih planeta biti potvrđene kao takve.
Sources: Live Science, BBC

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