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 …

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 …

Nov 5, 2025 · With our 2025 Moon Phase Calendar, you'll find the current Moon phase for tonight—plus, all the phases of the Moon for each day of the month.

1 day ago · The moon and sun share top billing in 2026. Kicking off the year's cosmic wonders is the moon, drawing the first astronauts to visit in more than 50 years.

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 · Most effort hitherto had been devoted to understanding the movements of the Moon through space, but now astronomers began to focus their attention on the character of …