Astronomers are one step closer to discovering another Earth, a planet that is roughly the same size and at enough distance from its star that it is in theory habitable. It is not far-fetched to say that this will very likely happen in the not-too-distant future.
The first extrasolar planets were discovered 15 years ago; now more than 400 have been found and at an accelerating pace. The early discoveries were gas giants on the order of Jupiter and Pluto and they orbited far too close to their stars. But as techniques have improved, astronomers are able to identify smaller, occasionally rocky, planets, orbiting far enough from their stars to be close to what is considered a habitable zone.
Especially sought are planets in a category known as “super-Earths,” those that are within 10 times the mass of Earth.
Now a team from the Harvard-Smithsonian Center for Astrophysics has discovered a planet orbiting a star in the Ophiuchus constellation that is only 2.7 times the size of Earth and 6.6 times as massive. And it is mainly water, alas, at 400 degrees F clouds of superheated steam cover boiling oceans.
Team leader David Charbonneau told The New York Times, with a certain understatement, “This probably is not habitable, but it didn’t miss the habitable zone by that much.”
Ophiuchus is 40 light-years from Earth, a huge distance but one that Charbonneau put into an arresting perspective for the Times: “Our own TV signals have already passed this star.”