Two planets orbiting a star 950 light-years from Earth are the smallest, most Earth-size alien worlds known, astronomers announced Tues., Dec. 20. One of the planets is actually smaller than Earth, scientists say. These planets, while roughly the size of our planet Earth, are circling very close to their star, giving them fiery temperatures that are most likely too hot to support life, researchers said. The discovery, however, brings scientists one step closer to finding a true twin of Earth that may be habitable. "We've crossed a threshold: For the first time, we've been able to detect planets smaller than the Earth around another star," lead researcher François Fressin of the Harvard-Smithsonian Center for Astrophysics in Cambridge, Mass., told SPACE.com. "We proved that Earth-size planets exist around other stars like the sun, and most importantly, we proved that humanity is able to detect them. It's the beginning of an era."
I think the title is a little mis-leading. IF they were inhabited, then you could include Alien in their title. Until we know differently, they are only discovered planets? No? Yes?
what does size really matter? If we found a planet 100x bigger than earth, with the exact same conditions.. wouldn't that just be all the better?
I don't think theory would allow for that. What this probably is, without reading, is they found the planets within the 3 planet range it is theorized planets can contain life due to their location.
The question is about "habitability". Given our limited experience, (one known habitable planet) we tend to assume that water is a prerequisite for life. Since you need a surface for liquid water that eliminates gas giants. It is generally believed that planetary bodies which have masses greater than around 10 times that of the Earth are no longer rocky/liquid bodies but become gas giants due to their strong gravitational field accumulating gas rapidly during the formation process. This mass limit provides useful constraints in determining a planet’s habitability. So we look for planets close to earth size. The problem was that big planets were easier to find given the distances involved and our technological limits. This article indicates that we now have the ability to at least find earth sized planets.
