On May 1, 1949, Neptune’s moon Nereid was discovered by the Dutch astronomer Gerard Kuiper. This was the second of 14 moons discovered at Neptune. It was also the last one to be discovered with certainty before NASA’s Voyager 2 spacecraft flew by Neptune in 1989. Astronomers suspected they had observed a third moon before, … Continue reading May 1, 1949: Nereid the Moon of Neptune is Discovered.