In 1980, Johnny Carson did a short spoof of Carl Sagan's Cosmos, which aired on PBS that year to huge ratings and rave reviews. Carson does a terrific impression of Sagan, latching onto Sagan's speech patterns and making a bunch of astute references to the actual science in the show. (He also created the "billions and billions" thing with this impression; Sagan never used that phrase in the show.)

Moments to watch for: the mention of Aristarchus, Voyager 1 transmission jokes (remember that Sagan had tried to convince NASA to have Voyager 1 take the "Pale Blue Dot" photo in 1980, though it wouldn't happen for another decade), Halley's Comet, and the establishment of the "billions and billions" gag. Enjoy:

And lest you think Carson didn't like Cosmos, here he is introducing a rerun of the show on KCET in 1984. Carson sincerely loved it: