On July 6, 1938, an American astronomer named Seth Barnes Nicholson discovered Jupiter’s moon Lysithea.
Nicholson spotted Lysithea from Mount Wilson Observatory in California, where he had previously discovered three more Jovian moons.
This was the tenth moon astronomers had found at Jupiter. As of June 2017, 69 moons have been found orbiting Jupiter.
Lysithea only measures about 11 miles in diameter and is part of Jupiter’s Himalia group, which contains five irregular moons that follow similar orbits and are thought to have a common origin.
Source: https://www.space.com/39251-on-this-day-in-space.html