The immense distances to the stars and the galaxies mean that we see everything ins pace int he past, some as they were before the Earth came to be. Telescopes are time machines.

We were wanderers from the beginning.

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.

Virtually every major technological advance in the history of the human species - back to the invention of stone tools and the domestication of fire - has been ethically ambiguous.

[Kepler] preferred the hard truth to his dearest illusions, and that is the heart of science.

In science it often happens that scientists say, 'You know that's a really good argument; my position is mistaken,' and then they would actually change their minds and you never hear that old view from them again. They really do it. It doesn't happen as often as it should, because scientists are human and change is sometimes painful. But it happens every day. I cannot recall the last time something like that happened in politics or religion.

Our species needs, and deserves, a citizenry with minds wide awake and a basic understanding of how the world works.