Who are we? We find that we live on an insignificant planet of a humdrum star lost in a galaxy tucked away in some forgotten corner of a universe in which there are far more galaxies than people.

The absence of evidence is not the evidence of absence.

Since, in the long run, every planetary society will be endangered by impacts from space, every surviving civilization is obliged to become spacefaring — not because of exploratory or romantic zeal, but for the most practical reason imaginable: staying alive.

When a honeybee dies it releases a death pheromone, a characteristic odour that signals the survivors to remove it from the hive. The corpse is promptly pushed and tugged out of the hive. The death pheromone is oleic acid. What happens if a live bee is dabbed with a drop of oleic acid? Then no matter how strapping and vigourous it might be, it is carried kicking and screaming out of the hive.

Not explaining science seems to me perverse. When you're in love, you want to tell the world.

One of the great commandments of science is: 'Mistrust arguments from authority.'

The Apollo pictures of the whole Earth conveyed to multitudes something well known to astronomers: On the scale of the worlds - to say nothing of stars or galaxies - humans are inconsequential, a thin film of life on an obscure and solitary lump of rock and metal