Solar Systems Like Ours

A couple of Ohio State astronomers involved in the search for extrasolar planets calculate that around 15 percent of the stars in the Milky Way have planetary systems similar to our Solar System. They acknowledge their study uses incomplete data, but think it gives astronomers a good idea of the probable abundance of such systems.

They also opine that most stars that have such systems will have fewer planets than orbit the Sun. That, too, is based on admittedly incomplete data.

Fifteen percent of stars constitute a rather small minority, but in absolute terms it suggests hundreds of millions of stars in our galaxy alone may harbor life similar to that found on Earth. That scattering is also consistent with the negative results so far reported in SETI searches. If we start with only a few hundred million stars instead of several billion, and assume advanced technological civilizations orbit at this instant only a small minority of those few hundred million, the nearest one to us could be quite a distance away. SETI, as its supporters have always argued, needs to be seen as a long term project.