NASA a anuntat astazi ca a descoperit, la aproximativ 40 de ani lumina de Terra, in jurul unei stele-pitici numai putin de sapte planete de tip terestru, dintre care trei planete sunt in zona care ar permite existanta apei lichide la suprfata si deci viata, una dintre ele fiind chiar banuita (pe criteriu de masa aparenta) ca ar avea apa lichida pe suprafata.
Descoperirea este una cu adevarat EXTRAORDINARA, mai ales daca tinem cont ca pana pe la mijlocul anilor „90, multi astronomi se indoiau de abundenta planetelor in jurul altor stele. Astazi avem deja confirmarea ca sistemele solare (stea/stele si planete) sunt ceva chiar banal, iar astazi aflam ca si existenta planetelor de tip terestru (ne referim aici la faptul ca o planeta sa fie compusa din roca si sa aiba dimensiuni similare cu Terra) nu sunt chiar atat de rare, daca un singur sistem solar are sapte.
Iar descoperirea este si ciudata in acelasi timp, pe langa entuziasmanta. Astfel, toate cele sapte planete sunt mai aproape de steaua-mama decat este Mercur de Soare. De asemenea cele sapte planete sunt extrem de apropiate incat cineva care ar sta pe una dintre ele ar putea sa distinga forme de relief de pe cele mai apropiate doua planete.
Apropierea extrema de steaua-mama mai inseamna si ca planetele sunt „blocate gravitational”, adica au aceiasi semisfera indreptata mereu spre soare, de aici rezultand faptul ca pe o jumatate de planeta este mereu ziua, pe cealalta mereu noapte si cel mai probabil clima pe cele sapte planete este una foarte…vantoasa si cu mari diferente de temperatura intre cele doua „fete”.
Descoperirea a fost facuta cu ajutorul telescopului spatial Spitzer si a altor telescoape terestre.
Pentru ca nu am timp, direct in engleza:
That’s why an announcement today from NASA is so exciting: The space agency, along with partners around the world, has found seven potentially Earth-like planets in the sweet spot orbiting a star 40 light-years away.
“It’s the first time that so many planets of this kind are found around a same star,” Michaël Gillon, the lead author of the Nature paper announcing the discovery, said in a press conference. “The seven planets … could have some liquid water and maybe life on the surface.”
Three of the planets are directly in the star’s habitable zone, meaning water can mostly likely exist on the surface of them. One of them, Gillon said, has a mass “strongly to suggest a water-rich composition.” And it’s possible that the other four could have liquid water, too, depending on the composition of their atmospheres, the astronomers said.
Sistemul solar TRAPPIST-1 (The Transiting Planets and Planetesimals Small Telescope (TRAPPIST)
The exoplanets orbit a star in the constellation Aquarius called Trappist-1. And it’s a solar system very different from our own.
For one, Trappist-1 is a tiny, “ultra-cool” dwarf star. It’s cool because it’s small: just about a tenth of the mass of our sun and about one-thousandth as bright. But its low mass allows its planets to orbit it very closely and remain in the habitable zone.
The distance at which the planets orbit Trappist-1 is comparable to the distance of Jupiter to its moons. All the planets are believed to be rocky, and are all believed to be around the size of Earth, give or take 10 to 20 percent.
Maybe the most exciting thing here is that these seven planets are very well suited for detailed atmospheric study,” Gillon said. The James Webb Space Telescope, set to launch in 2018, will have the ability to measure the chemical composition of exoplanet atmospheres. If the atmospheres contain telltale gases like ozone, oxygen, or methane, life could exist there. “We can expect that in a few years, we will know a lot more about these [seven] planets,” Amaury Triaud, another of the paper’s co-authors, said.
If this all sounds a bit familiar, it’s because astronomers announced three potentially habitable planets around Trappist-1 in May. Today’s reveal adds four more to the mix.
Right now, the astronomers are beginning to study the planets’ atmospheres with the telescopes they have. And from these observations, they feel fairly confident that the worlds are rocky. “For detailed characterization, we will need James Webb,” Triaud said.
In the meantime, we just have our imaginations to fill in the gap. This is an artist’s rendition of what the fifth planet in this bizarre solar system might look like. These planets are believed to be tidally locked to the star, each has a permanent day side and a permanent nice side. And because the planets are so close together, they’d appear in the sky like moons.
Sursa si articolul complet pe Vox.com