Moon — LLMpedia

Moon
Gregory H. Revera · CC BY-SA 3.0 · source
Name	Moon
Type	Natural satellite
Discovered	Prehistory
Mass	7.35×10^22 kg
Radius	1,737.4 km
Orbital period	27.3 days (sidereal)
Surface gravity	1.62 m/s^2

Contents

Moon The Moon is Earth's only natural satellite and the fifth-largest natural satellite in the Solar System. It influences tides, stabilizes Earth's axial tilt, and has been a focus of exploration by agencies and missions such as National Aeronautics and Space Administration, Soviet Union, European Space Agency, China National Space Administration, and private companies like SpaceX. Human activity around the Moon includes crewed missions, robotic landers, and proposed bases linked to programs such as Apollo program, Artemis program, Lunar Reconnaissance Orbiter, and Chang'e program.

Overview

The Moon orbits Earth and has been observed since antiquity by civilizations including Mesopotamia, Ancient Egypt, Ancient Greece, Maya civilization, Han dynasty, and Islamic Golden Age astronomers. Astronomical study advanced through instruments developed by figures like Nicolaus Copernicus, Galileo Galilei, Johannes Kepler, and Edmond Halley, and through modern observatories such as Palomar Observatory, Arecibo Observatory, and space telescopes including Hubble Space Telescope. Its exploration history prominently features programs and events like the Apollo 11 landing, the Luna programme, and recent missions from India's Chandrayaan programme.

Leading hypotheses posit that the Moon formed after a giant impact between early Earth and a Mars-sized body nicknamed Theia during the Hadean eon. This giant-impact hypothesis is supported by isotopic analyses performed by teams from institutions like California Institute of Technology, Massachusetts Institute of Technology, and Smithsonian Institution, and by numerical simulations produced by researchers affiliated with Jet Propulsion Laboratory and Imperial College London. Alternative ideas explored by scientists at University of Cambridge, University of Chicago, and Max Planck Institute include co-accretion and capture, but these are less consistent with oxygen isotope similarities observed between terrestrial and lunar samples returned by Apollo program missions.

The Moon's mean radius (~1,737 km), mass, density, and moment of inertia have been measured via tracking of spacecraft from organizations such as Jet Propulsion Laboratory and techniques developed at MIT and Stanford University. Its bulk composition includes a mantle and a core with estimates refined by seismology from instruments deployed during Apollo program missions and by analysis at facilities like Los Alamos National Laboratory and University of California, Berkeley. The surface exhibits a regolith whose properties were characterized by samples examined at Smithsonian Institution, Lunar and Planetary Institute, and laboratories at Johnson Space Center.

The Moon follows an elliptical orbit with eccentricity and inclination parameters measured by lunar laser ranging experiments conducted by teams from Harvard University, University of Maryland, and Observatoire de Paris. Tidal interactions with Earth have led to synchronous rotation producing near side and far side hemispheres studied by satellites including Lunar Reconnaissance Orbiter, Kaguya (SELENE), and LRO. Long-term orbital evolution involves angular momentum exchange with Earth affecting the length of day and lunar recession rates monitored by researchers at NOAA, NASA Goddard Space Flight Center, and European Southern Observatory.

The lunar surface hosts maria, highlands, impact basins, and rilles mapped by missions such as Clementine, Lunar Orbiter program, and Lunar Reconnaissance Orbiter. Major features include the South Pole–Aitken Basin investigated by Chandrayaan-2 and proposed for study by Artemis program planners. Rock types—anorthosite in highlands and basalt in maria—were characterized by analysis teams at Smithsonian Institution and universities like University of Arizona and Brown University. Volcanism, impact cratering, tectonic features, and potential volatiles such as water ice in permanently shadowed regions have been major research topics for groups at Caltech, University College London, and Russian Academy of Sciences.

Crewed landings by NASA's Apollo program between Apollo 11 and Apollo 17 delivered lunar samples to laboratories at Johnson Space Center and sparked scientific collaborations with institutions including University of Texas at Austin and Ohio State University. Robotic missions from agencies like Roscosmos, China National Space Administration, Indian Space Research Organisation, European Space Agency, and private firms have expanded surface and orbital studies through probes such as Luna programme landers, Chang'e program rovers, Chandrayaan-1, and commercial proposals linked to Artemis program. Future plans by NASA, JAXA, ESA, and commercial partners involve sustained presence, in-situ resource utilization, and science objectives coordinated with organizations like International Astronautical Federation.

The Moon has profound cultural roles across societies represented by mythologies from Ancient Greece, Norse mythology, Hinduism, Shinto, Mesoamerican religions, and Aboriginal Australian traditions. Literary and artistic works referencing lunar themes include creations tied to figures and works such as William Shakespeare, Jules Verne, H. G. Wells, Yoko Ono, Claude Monet, and compositions performed at venues like Royal Albert Hall and Carnegie Hall. Scientific popularization and public fascination have been promoted by organizations and events like Smithsonian Institution, Royal Astronomical Society, World Expo, and the Space Race between United States and Soviet Union, with contemporary cultural reflections in media franchises linked to NASA and private companies such as SpaceX.

Category:Natural satellites