“When heavy cloud decks enveloped the planet, they created a whole new surface that had never before existed, of high mountain ranges, tumbling ravines. Sometimes the clouds would create huge cliffs, sheer walls miles high into which shadows fell to… — Alan Shepard Copy Share Image
Life is fragile: it thrives only in a narrow range of temperatures between freezing and boiling. How lucky that our planet is just the right distance from the sun: a little farther, and the death of the perpetual Antarctic winter… — Leonard Susskind Copy Share Image
