Any sufficiently crisp question can be answered by a single binary digit-0 or 1, yes or no.

The near side of a galaxy is tens of thousands of light-years closer to us than the far side; thus we see the front as it was tens of thousands of years before the back. But typical events in galactic dynamics occupy tens of millions of years, so the error in thinking of an image of a galaxy as frozen in one moment of time is small.

For years I've been stressing with regard to UFOs that extraordinary claims require extraordinary evidence.

A multitude of aspects of the natural world that were considered miraculous only a few generations ago are now thoroughly understood in terms of physics and chemistry.

If our long-term survival is at stake, we have a basic responsibility to our species to venture to other worlds. Sailors on a becalmed sea, we sense the stirring of a breeze.

One of the greatest gifts adults can give - to their offspring and to their society - is to read to children.

An organism at war with itself is doomed.