It's the birthday of Carl Sagan, (books by this author) born in Brooklyn, New York (1934), who did more to promote space exploration than almost any other single person. He was a young astronomer advising NASA on a mission to send remote-controlled spacecrafts to Venus, when he learned that the spacecrafts would carry no cameras, because the other scientists considered cameras to be excess weight. Sagan couldn't believe they would give up the chance to see an alien planet up close. He lost the argument that time, but it's largely thanks to him that cameras were used on the Viking, Voyager, and Galileo missions, giving us the first real photographs of planets like Jupiter and Saturn and their moons.

Sagan also persuaded NASA engineers to turn the Voyager I spacecraft around on Valentine's Day in 1990, so that it could take a picture of Earth from the very edge of our solar system, about 4 billion miles away. In the photograph, Earth appears as a tiny bluish speck. Sagan later wrote of the photograph, "Look again at that dot. That's here. That's home. That's us. On it everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives... [on] a mote of dust suspended in a sunbeam."