Lunar horizon glow is a phenomenon due to which dust particles on the Moon's thin Atmosphere create a glow during lunar sunset. The Surveyor program provided data and photos of the phenomenon, Astronauts in the Apollo 15, and Apollo 17 missions observed them while in lunar orbit.

The atmosphere of the Moon is a very sparse layer of gases surrounding the Moon. For most practical purposes, the Moon is considered to be surrounded by vacuum. The elevated presence of atomic and molecular particles in its vicinity compared to interplanetary medium, referred to as "lunar atmosphere" for scientific objectives, is negligible in comparison with the gaseous envelopes surrounding Earth and most planets of the Solar System. The pressure of this small mass is around 3×10−15 atm (0.3 nPa), varying throughout the day, and in total mass less than 10 metric tonnes. Otherwise, the Moon is considered not to have an atmosphere because it cannot absorb measurable quantities of radiation, does not appear layered or self-circulating, and requires constant replenishment due to the high rate at which its gases are lost into space.