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 …

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

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 …

Dec 29, 2025 · 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.

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.

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 orbits Earth in the prograde direction and completes one revolution relative to the Vernal Equinox and the fixed stars in about 27.3 days (a tropical month and a sidereal month), and one …

Dec 29, 2025 · The moon and sun figure big in the new year’s lineup of cosmic wonders Here’s a rundown on what the universe has in store for us in 2026.

Dec 26, 2025 · Moon - Craters, Highlands, Maria: The Moon is a spherical rocky body, probably with a small metallic core, revolving around Earth in a slightly eccentric orbit at a mean distance of about …