Gerard Kuiper
Gerard Peter Kuiper, born Gerrit Pieter Kuiper (December 7, 1905 - December 23, 1973) was an American astronomer, born in the Netherlands.
Kuiper has discovered a number of satellites (moons) of the planets in the solar system, and suggested the existence of a belt outside Neptune's orbit, now named the Kuiper belt.
In the 1960s, Kuiper also helped identifying landing sites on the moon for the Apollo program.