"Alain Fournier" wrote in message
...
wrote:
Rodney Kelp wrote:



Yes there is evidence against it. The evidence isn't very strong
but we are now getting some serious data on the matter. Well
the evidence is somewhat strong that our solar system is
fundamentally different from the majority of planetary systems
around stars. It is much weaker about Earth-like planets being
very rare. Most planets found to date are Jupiter sized or bigger
in an elliptical orbit with periapsis less than 1 AU. If Jupiter
had an elliptical orbit with periapsis less than 1 AU, then
Earths orbit wouldn't be stable and Earth wouldn't be.

I suspect we've too few samples to draw any real conclusions. I remember
talking to an astronomer about extra-solar planets in the early 90's and he
was not then prepared to say they existed at all because the data was too
flimsy.

Given the size and scope, Earths might be rare but I do find it hard to
believe they are unique.

Dave