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Messier 84
Messier 84 (NGC 4374) is a giant elliptical galaxy in the Virgo Cluster, discovered by Charles Messier in 1781 and known for its central supermassive black hole.
Messier 85
Messier 85 (M85, NGC 4382) is a lenticular galaxy in the constellation Coma Berenices, about 60 million light-years away and a member of the Virgo cluster.
Messier 86
Messier 86 (M86, NGC 4406) is a giant lenticular galaxy in Virgo, about 52 million light-years away and one of the brightest members of the Virgo Cluster.
Messier 87
Messier 87, also called Virgo A, is a giant elliptical galaxy in the constellation Virgo about 54 million light-years away, with a supermassive black hole first imaged in 2019.
Messier 89
Messier 89 (M89, NGC 4552) is an elliptical galaxy in the Virgo Cluster, about 50 million light-years away and notable for its almost perfectly circular appearance.
Messier 92
Messier 92 (M92, NGC 6341) is a globular cluster of roughly 330,000 ancient stars in Hercules, about 27,000 light-years away and among the Milky Way's oldest and brightest.
Messier 94
Messier 94, also called the Cat's Eye Galaxy, is a spiral galaxy about 16 million light-years away in Canes Venatici, known for its bright starburst ring.
Messier 95
Messier 95 (M95, NGC 3351) is a barred spiral galaxy in the constellation Leo about 33 million light-years away, discovered in 1781 by Pierre Méchain.
Messier 96
Messier 96 (M96, NGC 3368) is an intermediate spiral galaxy about 35 million light-years away in Leo, discovered by Pierre Méchain in 1781 and roughly the size of the Milky Way.
Messier Catalogue
The Messier Catalogue is a list of 110 bright deep-sky objects, designated M1 through M110, compiled by French comet hunter Charles Messier to avoid mistaking them for comets.
Messier object
A Messier object, listed in the Messier catalog, is one of 110 star clusters, nebulae, and galaxies compiled by Charles Messier in the 18th century while hunting comets.
Messinian
The Messinian is the last age and stage of the Miocene, from 7.251 to 5.333 million years ago, named after Messina, Sicily, and known for the Messinian salinity crisis.
Mestranol
Mestranol (Ovastol) is a synthetic estrogen, the 3-methyl ether of ethinyl estradiol, that acts as a prodrug demethylated in the liver and was the estrogen in Enovid, the first birth control pill, approved in 1960.
Mesylate
Mesylate, also called methanesulfonate, is the anion CH₃SO₃⁻ and the name of a sulfonate ester group that converts an alcohol's hydroxyl into one of organic chemistry's best leaving groups.
Met Office
The Met Office, formally the Meteorological Office, is the United Kingdom's national weather service, founded in 1854 by Robert FitzRoy of HMS Beagle to improve safety at sea.
Met Office Hadley Centre
The Met Office Hadley Centre is the United Kingdom's primary source of climate change information and one of the world's principal climate research institutes, founded in 1990 as part of the Met Office.
Meta-analysis
A meta-analysis is a statistical method that combines the results of several independent studies into a single estimate of an effect, with a measure of uncertainty.
Meta-C–H functionalization
Meta-C–H functionalization is the selective transformation of the meta C–H bond of an aromatic ring, achieved through removable directing templates introduced by Jin-Quan Yu's group at Scripps in 2012.
Meta-ethnography
Meta-ethnography is a seven-phase interpretive method for synthesizing qualitative studies by translating their key concepts and metaphors into one another, developed by Noblit and Hare in 1983 and now well established in health research.
Meta-holography
Meta-holography, or metasurface holography, implements computer-generated holograms on ultrathin metasurfaces whose subwavelength nanostructures modulate light, achieving higher resolution, wider bandwidth, and broader viewing angles than conventional displays, with uses in 3D displays, security, and quantum optics.
Meta-regression
Meta-regression is a statistical technique in meta-analysis that regresses the effect sizes of multiple studies on study-level covariates, called moderators, to explain why studies differ.
Meta-synthesis
Meta-synthesis is a family of methods for integrating the findings of multiple qualitative studies into broader interpretations, concepts, or theory, rather than pooling them statistically.
Metabolic network modelling
Metabolic network modeling, also known as metabolic network reconstruction and simulation, is the mathematical representation of biochemical reactions in a cell, used to predict metabolite and flux behavior.
Metacentric height
The metacentric height (GM) is the vertical distance between a floating body's center of gravity and its metacenter, the standard measure of a ship's initial stability.
Metadynamics
Metadynamics is an enhanced-sampling molecular simulation method introduced by Alessandro Laio and Michele Parrinello in 2002 that uses a history-dependent bias to accelerate rare events and reconstruct free-energy surfaces.
Metaethics
Metaethics is the branch of philosophy studying the metaphysical, epistemological, and semantic presuppositions of moral thought; it emerged as a distinct field from G. E. Moore's Principia Ethica (1903).
metafor
metafor is a free, open-source package for the R statistical environment that provides functions for conducting meta-analyses, written and maintained by Wolfgang Viechtbauer and distributed on CRAN.
Metagratings
Metagratings are sparse periodic arrays of subwavelength scatterers that redirect electromagnetic, acoustic, or elastic waves into a chosen diffraction order while suppressing the others, proposed in 2017.
Metaheuristic
A metaheuristic, also known as a meta-algorithm, is a problem-independent framework for building heuristic optimization algorithms, used when problems like scheduling and vehicle routing are too complex for exact methods.
Metal
A metal is a chemical element that conducts heat and electricity, forms positive ions, and has a characteristic luster; iron makes up 90% of metal refined today.