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 …

Dec 29, 2025 · Like Earth, the Moon has a day side and a night side, which change as the Moon rotates. The Sun always illuminates half of the Moon while the other half remains dark.

5 days ago · Discover fascinating Moon facts—from its size and orbit to gravity, brightness, and temperature. Learn what makes Earth’s Moon truly unique.

We see the full moon when the sun is directly behind us, illuminating a full hemisphere of the moon when it is directly in front of us.

Dec 5, 2024 · A moon is an object that orbits a planet or something else that is not a star. Besides planets, moons can circle dwarf planets, large asteroids, and other bodies. Objects that orbit other …

1 day ago · NASA is moving into a new phase of space exploration, with major progress across human spaceflight, science missions, and advanced technology. In just one year, the agency has launched …

3 days ago · Moon, Earth’s sole natural satellite and nearest celestial body. Known since prehistoric times, it is the brightest object in the sky after the Sun. Its name in English, like that of Earth, is of …

The Moon Returning humans to lunar missions Why the moon? The Moon is one of Earth's closest habitable neighbors and provides an opportunity to gain valuable experience for missions to Mars …

The moon is the Earth's only natural satellite and the closest celestial object. Learn about the moon and some of the theories about the moon's origin.

As the four-person crew of Artemis II prepares to launch on a historic mission around the moon as soon as February, some experts are worried about the Orion spacecraft’s heat shield.