Himalia is one of the largest moons of Jupiter, discovered in 1904 by the astronomer Charles Dillon Perrine. It is classified as a member of the Himalia group, a collection of irregular moons that share similar orbits. Himalia has a diameter of about 170 kilometers (106 miles) and is primarily composed of ice and rock. The moon orbits Jupiter at a distance of approximately 11 million kilometers (6.8 million miles) and takes about 5.4 days to complete one orbit. Its surface is believed to be heavily cratered, indicating a long history of impacts. Himalia is also thought to have a very thin atmosphere, making it an interesting object of study in planetary science.