In geophysical terms, the Moon is a planetary-mass object or satellite planet. Its mass is 1.2% that of the Earth, and its diameter is 3,474 km (2,159 mi), roughly one-quarter of Earth's (about as wide as the contiguous United States).
The Moon makes Earth more livable, sets the rhythm of ocean tides, and keeps a record of our solar system's history. Explore NASA lunar science here.
Reference See what moon phase it is tonight and find out when you can see the rest of the moon phases for 2026. The Artemis 2 astronauts captured a unique image of the moon's "dark side" during ...
What is the moon made of, and how did it form? Learn about the moon's violent origins, how its phases shaped the earliest calendars, and how humans first explored Earth's only natural satellite half a century ago.
How big is the Moon? The Moon is Earth’s only permanent natural satellite, and it’s the fifth-largest satellite in our solar system. The Moon’s diameter is approximately 2,160 miles (3,475...
Moon, Earth ’s sole natural satellite and nearest large celestial body. Known since prehistoric times, it is the brightest object in the sky after the Sun. It is designated by the symbol ☽. Its name in English, like that of Earth, is of Germanic and Old English derivation. Did You Know?
From any location on the Earth, the Moon appears to be a circular disk which, at any specific time, is illuminated to some degree by direct sunlight. Like the Earth, the Moon is a sphere which is always half illuminated by the Sun, but as the Moon orbits the Earth we get to see more or less of the illuminated half. During each lunar orbit (a lunar month), we see the Moon's appearance change ...