Just two days after I had published my first post about life in the Universe, it was announced by two American astronomers, Vogt and Butler, that a new extrasolar planet has been discovered, the first one where life might be possible. See for example this New York Times article:
Reason for me to send publish an extra post, before I compose part two of the Great Debate post..
Gliese 581 is a so-called red dwarf star, located at a distance of 20 light-year from the Sun.
In itself a smallish nondescript star in our Milky Way, but interesting because it has been found that a number of planets orbit this star.
Four were known already, two more have been discovered now.
I have roughly given their position, size is not to scale. (keep in mind that the distance scale is logarithmic)
For comparison the Sun and some of its planets are also shown.
The blue band is the habitable zone, not too cold, not too hot, assuming water-based life.
Excitement is about planet g, right in the middle of Gliese’s habitable zone. This is a first. It has a mass of about 3 earth masses, and orbits Gliese in 37 days.
Only a pity, that the planet, like its 5 siblings, is tidally locked to Gliese, meaning that it always faces the same side to its sun (same as our moon is tidally locked to Earth). So it has a cold side and a hot side. If life exists there, it would probably be in the twilight zone