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 26, 2025 · 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 …

Dec 17, 2025 · The Earth and Moon are tidally locked. Their rotations are so in sync we only see one side of the Moon. Humans didn't see the lunar far side until a Soviet spacecraft flew past in 1959. …

The Moon: Complete and live astronomy data, visibility information, sky charts, graphs, and tools for sky-watchers at all levels.

On July 20, 1969, humans walked on the Moon for the first time.We look back at the legacy of our first small steps on the Moon and look forward to the next giant leap.

Nov 19, 2021 · What Is the Umbra? The umbra is the dark center portion of a shadow. The Moon's umbra causes total solar eclipses, and the Earth's umbra is involved in total and partial lunar eclipses.

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 …