Last spring, a team of Swiss, French and Portuguese astronomers announced the discovery of an exoplanet, a planet orbiting a star other than our own, Gliese 581c, in the constellation Libra. It can actually be seen, very dimly, with a good telescope. Over 200 exoplanets have been found outside of our solar system but this particular planet has some intriguing features unlike any of the others. Gliese 581c is 120 trillion miles away from Earth (that's pretty close in astronomical terms — 20.5 light years), it has a radius 50 times larger than Earth, its mass is five times larger than Earth's and has an orbital year of 13 days. It's still the smallest exoplanet ever to be discovered. Most importantly, Gliese 581c orbits around a red dwarf star that is 50 times cooler and a third the size of our Sun. Given the planet's closer proximity to this star, the planet is expected to be habitable, with a temperature similar to ours. Researchers also say that the surface might be covered in ice, oceans, lakes and rivers. Temperatures are predicted to fall between 32 and 102 Fahrenheit. Researchers think that Gliese 581c might be comprised of rock and would therefore its surface could be made up of land and water like ours. The possibility also exists that the planet is made of ice or that its surface has no land, only a never-ending expanse of ocean.

The first exoplanet discoveries occurred in 1995. These exoplanets were known as "Hot Jupiters" because their sizes were near to or even larger than the size of Jupiter, the largest planet in our solar system. They, however, are unable to support life because the distance to their parent stars is too close to sustain surface liquid water. Due to better technology, 237 exoplanets have been discovered since 1995, 20 of those since 2002. Out of all of these discoveries, Gliese 581c seems to be a good bet for finding extraterrestrial life — the only Earth-like discovery so far. Team member Xavier Delfosse of Grenoble University in France remarked that "Because of its temperature and relative proximity, this planet will most probably be a very important target of the future space missions dedicated to the search for extra-terrestrial life. On the treasure map of the Universe, one would be tempted to mark this planet with an X."