Yes, I know of him. Not read any of his books, but he is by far the most expert on the cosmos.
He wrote Contact which they made a movie from that I liked...
COSMOS had a huge effect on me when I was young. It opened my eyes to the wonders of the universe and answered so many questions that I didn't even know that I had.
CONTACT is one of the best SF films I've ever seen. For me, it's up there with 2001: A SPACE ODYSSEY.
However, for me, his most impressive achievement involved him driving a car full of children from coast to coast - east to west I think. And while he was doing that, he wrote a book as well. I have nothing but admiration for the man.