Alien worlds ranked on suitability for life

Of the hundreds of alien worlds, the catalog shows that 15 planets and 30 moons as potentially habitable

cosmic

a directory showing the planets and moons that could harbor extraterrestrial life was launched Monday by astronomers.

scientists have created the online catalog to make sense of a growing number of distant worlds that researchers have seen with modern telescopes.

They believe that the database will help astronomers, and others with interest, the comparison of distant worlds most liveable shows the researchers found.

More than 700 "exoplanets" have been discovered and verified beyond our own solar system in recent decades, while thousands of others awaiting confirmation of missions such as Kepler space telescope.

catalog habitable exoplanets, in essence, the ranks of the habitability of planets and moons according to three criteria. The surface temperature similar to Earth, and the ability to maintain the organisms in the bottom of the food chain

"An important result of these classifications is the ability to compare the exoplanets from best to worst candidates for life," said Abel Mendez, director of the laboratory planetary habitability at the University of Porto Rico at Arecibo.

Only a small proportion of alien worlds seem ripe for life as we know it. The catalog indicates that among the hundreds of candidates, 15 or more planets and moons, 30 are potentially habitable.

• catalog gives higher scores for the habitability of planets confirmed two. The first, Gliese 581d, is one of many surrounding one of the closest stars to Earth, a cool red dwarf star about 20 light-years away in the constellation Libra. The planet is about six times more massive than Earth.
The second planet HD85512b, orbiting a bright star 36 years away in the constellation Vela. This is more than three times heavier than our own planet. Most astronomers have discovered planets are gas giants like Jupiter, which are in orbits around their stars close.

astronomers classify planets by their scores on three different scales. The first is called the distance of the habitable zone, reflecting the position of the planet in the Goldilocks region of space around a star where conditions are neither too hot nor too cold for liquid water to form. Many astrobiologists believe that liquid water essential for life to flourish.

The second scale is called the similarity index of the Earth, which classifies the planets according to the proximity of its mass, radius, temperature and atmosphere likely to have coincided with our own planet .

The third level classifies the planets according to their "primary habitable world", which reflects whether the estimated surface temperatures are suitable for plant life and phytoplankton to grow. Land of low scores on this scale, because some grassroots organizations would be better at high temperatures.