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Thursday, November 24, 2011

Most liveable alien worlds ranked - 23rd Nov 2011

Scientists have outlined which moons and planets are most likely to harbour extra-terrestrial life.

Among the most habitable alien worlds were Saturn's moon Titan and the exoplanet Gliese 581g - thought to reside some 20.5 light-years away in the constellation Libra.

The international team devised two rating systems to assess the probability of hosting alien life.

They have published their results in the journal Astrobiology.

In their paper, the authors propose two different indices: an Earth Similarity Index (ESI) and a Planetary Habitability Index (PHI).

"The first question is whether Earth-like conditions can be found on other worlds, since we know empirically that those conditions could harbour life," said co-author Dr Dirk Schulze-Makuch from Washington State University, US.

"The second question is whether conditions exist on exoplanets that suggest the possibility of other forms of life, whether known to us or not." Read More

EARTH SIMILARITY INDEX

  • Earth - 1.00
  • Gliese 581g - 0.89
  • Gliese 581d - 0.74
  • Gliese 581c - 0.70
  • Mars - 0.70
  • Mercury - 0.60
  • HD 69830 d - 0.60
  • 55 Cnc c - 0.56
  • Moon - 0.56
  • Gliese 581e - 0.53