Top 5 Potentially Habitable Alien Worlds
Astronomers have found more than 700 planets beyond our solar system, and thousands more await confirmation by follow-up observations. Many of these alien worlds are too hot or too cold to support life as we know it, but researchers have found a few that appear to be much more hospitable.
On July 19, scientists at the University of Puerto Rico at Arecibo's Planetary Habitability Laboratory released a list of the top five potentially habitable exoplanets. Here's a brief rundown of the PHL's best candidates:
1. Gliese 581g
This rocky world was announced in September 2010 and has been controversial ever since, with some researchers casting doubt on its existence and its discoverers remaining firmly behind their find.
Gliese 581g, which is located just 20 light-years away, is likely two to three times as massive as Earth and zips around its parent star every 30 days or so. This orbit places the planet squarely in its star's "habitable zone" — that just-right range of distances where liquid water, and perhaps life as we know it, could exist.
This slide show was originally posted by Mike Wall, senior space writer of SPACE.com