If you took all the sand from all the beaches, all the desserts, and all the oceans and called that the Universe, our whole solar system would be less than one grain of sand.

There is little chance that aliens from two societies anywhere in the Galaxy will be culturally close enough to really 'get along.' This is something to ponder as you watch the famous cantina scene in Star Wars. ... Does this make sense, given the overwhelmingly likely situation that galactic civilizations differ in their level of evolutionary development by thousands or millions of years? Would you share drinks with a trilobite, an ourang-outang, or a saber-toothed tiger? Or would you just arrange to have a few specimens stuffed and carted off to the local museum?

The split between religion and science is relatively new. Isaac Newton, who first worked out the laws by which gravity held the planets and even the stars in their traces, was sufficiently impressed by the scale and regularity of the universe to ascribe it all to God.

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

[O]ne might ask why, in a galaxy of a few hundred billion stars, the aliens are so intent on coming to Earth at all. It would be as if every vertebrate in North America somehow felt drawn to a particular house in Peoria, Illinois. Are we really that interesting?

There is a point of view among astronomical researchers that is generally referred to as the Principle of Mediocrity. ... If the Sun and its retinue of worlds is only one system among many, then many other systems will be like ours: home to life. Indeed, to the extent that this is true, we should be prepared for the possibility that, even in the Milky Way galaxy, billions of planets may be carpeted by the dirty, nasty business known as life.

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.