I met him once when I was an undergraduate at U.C. Berkeley in 1973. He was giving a colloquium in the Astronomy Department there. I have never seen him since, since the professional meetings he attends are very different than the ones I go to. I recall his deep black hair, worn more or less as you see it in 'Cosmos', and that he was no taller than I am. He spoke with a very distinct speech pattern, which later became his hallmark.