The Moon
The Moon is Earth’s only natural satellite—a rocky, cratered body about one‑quarter the diameter of Earth, orbiting at an average distance of approximately 384,400 km. It influences tides, stabilizes Earth’s axial tilt, and was formed about 4.5 billion years ago following a collision between Earth and a Mars-sized object.
Source: science.nasa.gov
APODs including "The Moon"
The First Lunar Observatory
08/06/1996
The first and only lunar astronomical observatory was deployed by the Apollo 16 crew in 1972. The Far Ultraviolet Camera / Spectrograph used a 3-inch diameter telescope to photograph the Earth, various nebulae, star clusters, and the Large Magellanic Cloud. The camera is seen above placed in the shadow of the Lunar Module so it would not overheat. A leg of the Lunar Module enters the picture from the left. The camera took pictures in ultraviolet light which would normally be blocked by the Earth's atmosphere. The Far Ultraviolet Camera was created by George Carruthers (NRL), had a field of view of 20 degrees, and could detect stars having visual magnitude brighter than 11. 178 images were recorded in a film cartridge which was returned to Earth. The observatory stands on the Moon even today.