Arthur C. Clarke's Three Laws:

When a distinguished but elderly scientist states that something is possible, he is almost
certainly right. When he states that something is impossible, he is very probably wrong.

The only way of discovering the limits of the possible is to venture a little way past them into the impossible.

Any sufficiently advanced technology is indistinguishable from magic.

Other good observations by Clarke:

I'm sure the universe is full of intelligent life. It's just been too intelligent to come here.

If we have learned one thing from the history of invention and discovery, it is that, in the long run — and often in the short one — the most daring prophecies seem laughably conservative.

Rare Earth was published in 2000. That seems pretty recent, but between such things as the Mars rovers wandering around, sniffing and tasting (last telemetry received in 2005 as I recall, so apparently they are now defunct), and all the work being done with the Hubble Telescope and such, the fields of astronomy, cosmology, and exobiology are moving quite quickly, with new data being received every day. By the time a book is published, some of the information (and the speculation based in it) is outdated.

This is why I DO read books in these fields—BUT rely for really recent findings on periodicals such as "Astronomy" magazine, plus a couple of web sites. And a friend who works in the University of Washington's astrobiology department.

Don Firth