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 …

Dec 20, 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 …

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 …

Dec 4, 2025 · What is the Moon Phase today? Use our 2023 Moon Phase Calendar to find dates and times of the full Moon, new Moon, and every phase in between. Beyond the phases of the …

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 15, 2025 · Research shows a full moon can modestly affect sleep, but its influence on mental health is much less certain.

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 …

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

Sep 18, 2025 · The eight lunar phases are, in order: new Moon, waxing crescent, first quarter, waxing gibbous, full Moon, waning gibbous, third quarter, and waning crescent. The cycle …

Dec 14, 2025 · Kepler wrote a remarkable work of science fiction, Somnium (“The Dream”), that describes the life of imagined inhabitants of the Moon and correctly portrays such facts as the …