Earth Like Planet a Significant Discovery

Artist Impression of the Alpha Centuri Bb system. Image courtesy of European Southern Observatory (ESO). Licenced under Creative Commons.

You have probably heard that a team of European astronomers from the Observatory of Geneva and from the Centre for Astrophysics of the University of Porto have discovered an Earth sized planet in orbit around Alpha Centauri B. The Alpha Centauri system is our solar system's closest neighbour.

Since the first extrasolar planet was confirmed in 1988 by Canadian astronomers Bruce Campbell, G. A. H. Walker, and Stephenson Yang, 842 planets have been identified. But until this most recent discovery, all of these planets have been giants, similar in size of our own solar system's Neptune or Jupiter. This is not because giant planets are more numerous than smaller planets, but because current detection techniques make large planets significantly easier to find.

So what is the significance of the discovery of an Earth sized planet virtually in out back yard? If Earth sized planets were rare, you would expect that they would be widely scattered. The odds of finding another such rare planet so close would be very small. This discovery means that Earth sized planets could very well be quite common.

This new planet is very close to its parent star. With surface temperatures likely in the 1200 °C range, Alpha Centauri Bb is unlikely to be the home for life. But, with 100 billion stars in our galaxy, and 100 billion galaxies in the known universe, the number of earth sized planets is probably staggering. The odds of many of these planets being found in the so called "Cinderella Zone", where the conditions for life are ideal, could be very high. We are very probably not alone!