A Pretty Good Moon for You, Shoemaker!

Abstract

If 1969 were a time for exploring craters on the moon, it was also a time to start looking for other things in space—not just craters but the comets and asteroids that cause the craters. It turned out that Cal-tech’s Palomar Observatory had a small 18-inch diameter Schmidt telescope that was not being used very much. Palomar is most famous for its mighty 200-inch reflecting telescope, but three other telescopes atop that mountain northeast of San Diego also do important work. As Palomar’s first telescope, the 18-inch has a noble history. Astronomer Fritz Zwicky used it to photograph fields of distant galaxies, and in these galaxies he discovered many exploding stars called supernovae. The 18-inch telescope is a photographic telescope capable of taking pictures of large areas of the sky at once—each film covers 8.75 degrees of sky, the equivalent of more than 17 full moons lined up. On a single film, a searcher could record a large nugget of sky. Here was an ideal telescope for searching for comets and asteroids.