Seth Shostak

Huge. There may not be enough money for me to finish this sen

Our galaxy has roughly a trillion planets. Hard to imagine that they're ALL sterile.

Traveling between galaxies is hard ... typical distances are millions of light-years. That's a trip that, even with our fastest rockets, would take longer than the current age of the universe. That's a long time to be sitting in the middle seat ...

I think this is an EXCELLENT question! It could be the superior fast food in this country. Mainly, however, it's likely to be the fact that one-third of the American populace believes that aliens are visiting ... and hey, if they're here, they're not going to be spending all their time in Lower Moldavia.

Well, the real problem is ... lack of money! We're not hiring too many folks these days ... which is a real shame.

We know nothing about the overwhelming majority, but NASA's Kepler telescope will tell us what fraction are habitable ... and it's not unreasonable to assume that the fraction will be somewhere between one in a thousand and one in ten. Even with the pessimistic number, that's still a billion habitable worlds ... just in OUR galaxy.

Good question. First, we look at some of the signal characteristics to see if it's just a transmitter bolted to the Earth, in which case we can throw it out. But the real test is to move the antennas around a bit, and establish that the signal's coming from one spot on the sky, that moves across the sky at the same rate as the stars.

That's a signal comment!

Glad to hear it's legal.

Bunny ranch? Is that a kind of salad dressing?

Not very far. In fact, not even the distance of the nearest star for many signals (such as TV). But our radars ARE very powerful, and could be found with technology analogous to ours from tens or hundreds of light-years distance.