The number of habitable worlds in our galaxy is certainly in the tens of billions, minimum, and we haven't even talked about the moons. And the number of galaxies we can see, other than our own, is about 100 billion.

Like prospecting in the 19th century, reconnaissance of the asteroids would of necessity take place in an arena where trouble is likely and help is distant. Heroic stories of individual triumph and failure, set on landscapes never seen by humankind, are in the cards.

The search for extra-terrestrial life is a failure until that moment when it suddenly becomes a success.

Neil Armstrong was no Christopher Columbus. In most respects, he was better. Unlike the famous fifteenth century seafarer, Armstrong knew where he landed. He also spent his time in public service, not in jail, and his passing was marked by world-wide encomiums. He ended his days as a celebrated explorer rather than a royal inconvenience.

Despite the impression you may have from watching too much TV, movies are not about reproducing reality. Theyre about telling stories.

No heating system can deliver perfectly uniform temperatures throughout a house, and drafts can magnify the perceived difference in temperatures. Try walking around with a thermometer.

Five centuries from now - barring unimaginable catastrophe - the moon will be developed real estate. There's economic incentive to exploit the moon - the helium-3 will be useful in powering fusion reactors, and the rare earth elements could supplant the limited terrestrial supply of these materials.

While about one-third of Americans believe in ghosts, you won't find many exhibits on these spooky beings down at the local science museum. Why? Well, one explanation that you might consider, ghosts are just figments of our highly fertile imaginations!

If this is the only planet on which not only life, but intelligent life, has arisen, that would be very unusual.