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Lunar eclipses of the 21st century
The lunar eclipses of the 21st century, also listed as the list of 21st-century lunar eclipses, are the 228 eclipses occurring between 2001 and 2100, including 85 total eclipses.
Lunar eclipses of the 22nd century
The lunar eclipses of the 22nd century are the 238 eclipses predicted between January 2101 and December 2200, comprising 81 penumbral, 88 partial, and 69 total eclipses.
Lunar effect
The lunar effect is the claimed influence of the Moon's phases, especially the full moon, on human behavior and health; large-scale research has found no reliable connection.
Lunar phase
A lunar phase, also called a moon phase, is one of the recurring apparent shapes of the Moon as seen from Earth, repeating every 29.5 days.
Lunar resources
Lunar resources, also called Moon mining targets, are materials on the Moon usable for space activity, including polar water ice, regolith oxygen and metals, and helium-3; none are yet extracted.
Lunar theory
Lunar theory is the mathematical description of the Moon's motion around the Earth under the gravitation of the Earth and the Sun, serving for three centuries as the principal testing ground for perturbation theory.
Lunar water
Lunar water, also called water on the Moon, is water on or beneath the Moon's surface, including ice in permanently shadowed polar craters, confirmed by spacecraft since the 1990s.
M-type asteroid
M-type asteroids, also called M-class asteroids, are a class of asteroid with moderate albedo and featureless spectra, interpreted as metallic nickel-iron bodies; the largest member is 16 Psyche.
Magma ocean
A magma ocean is a global layer of molten silicate rock on a young planet, formed by accretion, core formation, and giant impacts early in the Solar System.
Magnetic cloud
A magnetic cloud is a transient solar-wind structure produced by a coronal mass ejection, marked by strong fields, smooth field-direction rotation, and low proton temperature.
Magnetic field of Jupiter
The magnetic field of Jupiter, discovered in 1955, is about 20 times stronger than Earth's, driving a magnetosphere 20 million kilometers wide with intense radiation belts.
Magnetosphere
A magnetosphere is the region of space around a planet or moon controlled by its magnetic field, deflecting the solar wind; Earth's shields its atmosphere and drives auroras.
Magnetosphere of Uranus
The magnetosphere of Uranus, discovered by Voyager 2 in January 1986, is unusually tilted and offset, so its geometry changes dramatically over the planet's 17-hour day.
Magura Fossae
Magura Fossae is a 600-km-wide fossa (tectonic trough) system on Venus at 12°S, 332.5°E, in quadrangle v43; IAU-approved in 1997 and named for an East Slavic winged warrior maiden.
Main-belt comet
A main-belt comet (MBC) is a small Solar System body in the main asteroid belt between Mars and Jupiter showing comet-like activity from sublimating ice, first recognized as a class in 2006.
Makemake
Makemake is a dwarf planet in the Kuiper Belt beyond Neptune, discovered in 2005 and named in 2008; it is that belt's second-brightest object after Pluto.
Man in the Moon
The Man in the Moon is a figure of Western folklore: a face people see in the Moon's dark lunar maria, an illusion known as pareidolia.
Manhattanhenge
Manhattanhenge, also known as the Manhattan solstice, is an event four evenings a year when the setting sun aligns with Manhattan's east-west cross streets in New York City.
Manto Fossae
Manto Fossae: a 536 km system of fossae, long narrow linear depressions, on Venus at 63.6°N, 64.9°E, IAU-named in 1991 for a Greek war goddess, part of the Sigrun-Manto deformation belt near Fortuna Tessera.
March 2025 lunar eclipse
The March 2025 lunar eclipse was a total lunar eclipse on the night of March 13–14, 2025, the first since 2022, best visible from North and South America.
March equinox
The March equinox, also called the northward or vernal equinox, is the moment the Sun crosses Earth's equator moving north, around March 19 to 21, starting northern spring.
Mars
Mars is the fourth planet from the Sun, a cold desert world about half Earth's size whose thin atmosphere once allowed rivers and lakes billions of years ago.
Mars Exploration Program
The Mars Exploration Program is NASA's long-term robotic program to study Mars, created after the 1993 loss of Mars Observer, with rovers and orbiters pursuing life, climate, and geology goals.
Maunder Minimum
The Maunder Minimum was a period from 1645 to 1715 when sunspot activity on the Sun all but stopped, coinciding with the coldest part of Europe's Little Ice Age.
Mean anomaly
The mean anomaly is a Keplerian orbital element, an angle increasing steadily by 360 degrees each orbit that specifies a body's position along its elliptical orbit.
Meanings of minor planet names: 8001–9000
Meanings of minor planet names: 8001–9000 is the portion of the IAU's minor-planet naming record covering numbered objects 8001 through 9000, named mostly in the late 1990s and 2000s.
Meanings of minor-planet names
Meanings of minor-planet names are recorded by the IAU's Working Group Small Body Nomenclature, which approves each asteroid name, at most 16 characters, with a citation explaining its origin.
Meanings of minor-planet names: 1–1000
The list of meanings of minor-planet names 1–1000 covers the first thousand numbered minor planets, from 1 Ceres, discovered in 1801, to 1000 Piazzia, named in 1923.
Meanings of minor-planet names: 1001–2000
Meanings of minor-planet names: 1001–2000 is the naming record for the second thousand numbered minor planets, objects discovered chiefly photographically in the 1920s and 1930s and named afterward.
Mercury (planet)
Mercury, the planet, is the smallest planet and the closest to the Sun, a rocky world with a giant iron core and no moons or rings.