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?
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.
Track the moon phase today with our interactive moon phase calculator. Get details on the current moon phase and the next full moon date.
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...
Discover what we know about Earth's lunar companion with the latest moon news, features and articles.
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.