posted on Jul, 13 2004 @ 11:06 AM
This does not answer directly your question, but it is one of the best ones that I have seen on the subject about planets and life.
This part of the site touches on the Habitable planets outside the solar system.
Is there life on planets outside the solar system?
The ultimate goal of the Origins program is of course not just to discover which extra-solar planets might be conducive for life, but rather to detect
actual evidence for life on one or more of those planets, in order to answer the age-old question, "Are we alone?"
I believe that the estimate for stars is around. 1,000,000,000,000,000,000,000. This is not planets of course. So, I would guess figure it 10
According to JPL, it looks like 123 extrasolar planets have been confirmed. The problem s that they are just too far out in space to be able to see
well and confirm.
[edit on 13-7-2004 by JCMinJapan]