Within the scientific community, there is healthy skepticism. And the question is, 'How do you ever get to a meaningful null result? How long and how hard do SETI scientists have to look for extraterrestrial intelligence and find nothing before they say, 'There is nothing. We are alone.'

The universe has told us the most common types of planets are small planets, and our study shows these are exactly the ones that are most likely to be orbiting Alpha Centauri A and B.

I hope that vigorous space exploration continues and that humankind will have a space station that resides between Earth and the moon. Outside the gravitational field of Earth, we could launch robotic spacecraft to other destinations in our solar system.

A 'serious' scientist in 1992 or 1993 had to admit the possibility that planets were really rare, that most stars might not have planets. We've gone from there to here - where most stars have planets.