M series (Japanese rockets)
M star
M1 (NGC 1952, Crab Nebula)
M2 (NGC 7089, globular cluster)
M3 (NGC 5272, globular cluster)
M4 (NGC 6121, globular cluster)
M5 (NGC 5904, globular cluster)
M6 (NGC 6405, Butterfly Cluster)
M7 (NGC 6475, Ptolemy's Cluster)
M8 (NGC 6523, Lagoon Nebula)
M11 (NGC 6705, Wild Duck Cluster)
M13 (NGC 6205, Great Cluster in Hercules)
M16 (NGC 6611, open cluster)
M17 (NGC 6618, Omega Nebula)
M20 (NGC 6514, Trifid Nebula)
M27 (NGC 6853, Dumbbell Nebula)
M31 (NGC 224, Andromeda Galaxy)
M32 (NGC 221, companion to M31)
M33 (NGC 598, Triangulum Galaxy)
M36 (NGC 1960, open cluster)
M37 (NGC 2099, open cluster)
M38 (NGC 1912, open cluster)
M41 (NGC 2287, open cluster)
M42 (NGC 1976, Orion Nebula)
M44 (NGC 2632, Praesepe)
M45 (Pleiades)
M50 (NGC 2323)
M51 (NGC 5194, Whirlpool Galaxy)
M52 (NGC 7654, open cluster)
M57 (NGC 6720, Ring Nebula)
M63 (NGC 5055, Sunflower Galaxy)
M64 (NGC 4826, Black Eye Galaxy)
M72 (NGC 6981, globular cluster)
M74 (NGC 628, spiral galaxy)
M76 (NGC 650, Little Dumbbell Nebula)
M80 (NGC 6093, globular cluster)
M81 (NGC 3031, spiral galaxy)
M82 (NGC 3034, companion to M81)
M87 (NGC 4486, elliptical galaxy)
M94 (NGC 4736, spiral galaxy)
M97 (NGC 3587, Owl Nebula)
M101 (NGC 5457, spiral galaxy)
M103 (NGC 581, open cluster)
M104 (NGC 4594, Sombrero Galaxy)
M110 (NGC 205, companion to M31)
M-2 (lifting body)
M2P2 (Mini-Magnetospheric Plasma Propulsion)
maar
MABES (Magnetic Bearing Satellite)
Mach angle
Mach number
machine
Mach's principle
MACHO Project
MACHOs
Mack, John E. (1929-2004)
Maclaurin, Colin (1698-1746)
Maclaurin trisectrix
MacMahon, Percy Alexander (1854-1929)
MacMahon squares
macroevolution
macromolecule
macroturbulence
MACSAT (Multiple Access Communications Satellite)
macula
Mädler, Johann Heinrich von (1794-1874)
Maestlin, Michael (1550-1631)
Maffei 1 Group
mafic
Magdeburg Project
Magellan (Venus probe)
Magellan Telescopes
Magellanic Clouds
Magellanic Stream
maghemite
magic cube
magic square
magic tour
magma
magnesium
magnet
magnetar
magnetic bottle
magnetic cataclysmic variable
magnetic constant
magnetic field
magnetic field lines
magnetic field strength
magnetic flux
magnetic flux density
magnetic levitation launch-assist
magnetic monopole
magnetic quantum number
magnetic resonance imaging (MRI)
magnetic star
magnetic susceptibility
magnetism
magneto
magnetogram
magnetograph
magnetohydrodynamics
magnetometer
magnetopause
magnetoplasmadynamic thruster
magnetosheath
magnetosphere
Magnetosphere Probe
magnetotactic bacteria
magnetotail
magnetotaxis
magnification
magnitude
magnitude, of the tenth brightest member
magnitude scale
Magnum
Magsat (Magnetic Field Satellite)
Maia (20 Tauri)
main asteroid belt
main diagonal
main sequence
main-sequence fitting
main-sequence turnoff
main stage
major axis
major planet
majority rule circuit
Makarov, Oleg G. (1933-)
Maksutov telescope
malaria
male reproductive accessory glands
male reproductive duct system
male reproductive system
male sexual response and hormone control
Malfatti circles
malic acid
Malin-1
Malina, Frank J. (1912-1981)
Malmquist effect
malnutrition
Malpighi, Marcello (1628-1694)
Malpighian layer
Malthus, Thomas Robert (1766-1834)
maltose
Malyutka
mammal
mammary glands
mancala
Mandelbrot, Benoît B. (1924-)
Mandelbrot set
mandible
maneuverability
manganese
manganese star
Manhigh, Project
MANIA
manifold
Manned Maneuvering Unit (MMU)
Manned Orbiting Laboratory (MOL)
MANNED SPACEFLIGHT
manometer
Mantell, Captain Thomas F. (1922-1948)
mantle
many-body problem
many-worlds theory
MAP (Microwave Anisotropy Probe)
MAP (Multichannel Astrometric Photometer)
MAPS
marble
Marconi, Guglielmo (1874-1937)
Marcy, Geoffrey W. (1954-)
MARECS
Marfa Lights
Marfan syndrome
Margulis, Lynn (1938)
maria
Maria family (of asteroids)
Mariner series
Mariner 9
Marius, Simon (1573-1624)
Markarian Chain
Markov chain
Marquardt space sled
MARS
Mars
Mars, ammonia on
Mars, atmosphere
Mars, canals
Mars, caves
Mars, changes on
Mars, communication with
Mars, dust devils
Mars, life
Mars, meteorites from
Mars, methane on
Mars, moons
Mars, oppositions
Mars, past conditions
Mars, polar caps
MARS, UNMANNED SPACECRAFT
Mars, vegetation
Mars, water
Mars 1969 A/B
Mars 96
Mars Climate Orbiter
Mars Exploration Rovers
Mars Express
Mars "face"
Mars Global Surveyor (MGS)
Mars meteorites
Mars Microprobe Mission
Mars Observer
Mars Pathfinder
Mars Phoenix Lander
Mars Phoenix Lander photos
Mars Polar Lander
Mars Reconnaissance Orbiter
Mars Science Laboratory
Mars Scout
Mars Surveyor 98
Mars trojan
Mars 2001 Odyssey
Mars-crosser
Marshall, George C. (1880-1959)
Marshall Space Flight Center
Marsnik
marsupial
Martian Chronicles, The
Martian "fossils" controversy
Martingale system
Mascall, Eric Lionel (1905-1993)
Mascheroni construction
mascon
maser
Maskelyne, Nevil (1732-1811)
mass
mass deficiency
mass discrepancy
mass driver
mass extinction
mass function
mass loss
mass number
mass ratio
mass spectrometry
mass transfer
mass-energy relationship
massif
mass-luminosity ratio
mass-luminosity relation
mass-luminosity-radius relation
mass-radius relation
mast cell
mastectomy
MASTIF (Multiple Axis Space Test Inertia Facility)
mastoid bone
Matador
Matagorda Island
materialism
mathematical lifespan
MATHEMATICIANS
MATHEMATICS
mathematics
mathematics, as a universal language
Mathilde (minor planet 253)
Matrioshka brain
matrix
matter
Matthew, William Diller (1871-1930)
Mattingly, Thomas K. II (1936-)
Maul, Alfred (1864-1941)
Mauna Kea observatories
Maunder, Edward Walter (1851-1928)
Max Q
maxilla
Maxwell, James Clerk (1831-1879)
Mayall Telescope
Mayor, Michel (1959-)
maze
McAuliffe, S. Christa Corrigan (1948-1986)
McCandless, Bruce II (1937-)
McDermot, Murtagh
McDivitt, James A. (1929-)
McDonald, James
McDonald Observatory
McDonnell Douglas
McIntosh (sunspot) scheme
McKay, Christopher P.
McKay, David S.
M-class asteroid
McMath-Pierce Solar Telescope
MCSA
MDS (Mission Demonstration test Satellite)
Me star
mean
mean corpuscular hemoglobin (MCH)
mean corpuscular hemoglobin concentration (MCHC)
mean corpuscular volume (MCV)
mean motion
mean motion resonance
mean orbital elements
mean parallax
mean place
mean sun
measles
measure
measure theory
measuring and weghing puzzles
Méchain, Pierre François André (1744-1804)
mechanical advantage
mechanical puzzle
mechanics
MECO (main engine cutoff)
medial
medial triangle
median
median nerve
mediastinum
medieval philosophy, related to the possibility of extraterrestrial life
mediocrity, principle
medium Earth orbit (MEO)
medulla
medulla oblongata
medusa
megahertz (MHz)
megamaser
meiosis
Meissa (Lambda Orionis)
Meissner effect
Mekbuda (Zeta Geminorum)
melanin
melanocyte-stimlating hormone (MSH)
melanoma
melanoma treatment
melatonin
melting point
memory (computer)
Menaechmus (c.380-c.320 BC)
Mendel, Johann Gregor (1822-1884)
mendelevium
Mendeleyev, Dmitri Ivanovich (1834-1907)
Mendelian inheritance
Menger sponge
meninges
meningitis
meniscus
meniscus lens
Menkalinan (Beta Aurigae)
Menkent (Theta Centauri)
Menkib (Xi Persei)
Mensa (constellation)
menstruation
Mentor
Menzel, Donald Howard (1901-1976)
Merak (Beta Ursae Majoris)
mercury (element)
Mercury (planet)
Mercury, life
Mercury, rotation
Mercury Project
Mercury Seven
Mercury Thirteen
Mercury-Atlas
Mercury-ELINT
mercury-manganese star
Mercury-Redstone
meridian
Meridiani Planum
meristem
Merope (23 Tauri)
Merope Nebula (NGC 1435)
Mersenne, Marin (1588-1648)
Mersenne number
Mersenne prime
mesa
mesentery
mesoderm
mesoglea
meson
mesopause
mesophiles
mesophyll
mesosiderite
mesosphere
mesothelioma
mesothelium
Mesozoic era
MESSENGER (Mercury Surface, Space Environment, Geochemistry and Ranging)
messenger probe
messenger RNA
Messerschmitt, Wilhelm (1898-1978)
Messier, Charles Joseph (1730-1817)
Messier Catalogue
META, Project
META II, Project
metabolic syndrome
metabolism
metabolite
metacarpal
metal
metallic bond
metallic crystal
metallic hydrogen
metallicity
metalloid
metal-poor star
metal-rich star
metamorphic
metastasis
metatarsal
metazoan
meteor
Meteor (Russian satellites)
meteor, sporadic
meteor shower
meteor storm
meteor train
meteorite
meteorite shower
METEORITES, FAMOUS
meteorites, from Mars
meteorites, organic matter in
meteoroid
meteoroid stream
meteoroid swarm
meteorological satellite
METEORS AND METEORITES
Meteosat
meter
methanal
methane
methane rocket engine
methanogens
methanol
method of exhaustion
Metis
Metonic cycle
MetOp (Meteorological Operational) satellites
metric
metric prefixes
metric space
metrizable
Metrodorus of Chios (fourth century BC)
Meudon Observatory
Miaplacidus (Beta Carinae)
mica
Mice, The (NGC 4676 A and B)
Michell, John (1724-1793)
microarray technology
microbe
microbes, temperature ranges of
microbiology
MICROBIOLOGY
microbody
microcline
microevolution
microfilament
microgravity
MicroLab
microlensing
Microlensing Observations in Astrophysics (MOA)
Microlensing Planet Search (MPS) Project
Micromegas
micrometeorites
micrometeoroid protection
micronutrient
microorganism
microphone
micropyle
microquasar
MicroSat
microsatellite
microscope
microscope argument
Microscopium
microspheres
microtubule
microturbulence
Microwave Observing Program (MOP)
microwave plasma thruster
microwave radiation
microwave window
microwave-induced fusion propulsion
MIDAS (Missile Defense Alarm System)
midbrain
midcourse
middle ear
middle lamella
MIDEX (Medium-scale Explorer)
mid-ocean ridge
midpoint
Mid-Infrared Large-well Imager (MIRLIN)
Midori (a.k.a. ADEOS)
Mie scattering
Mightysat
Milankovich cycles
mile
MILITARY INSTALLATIONS
MILITARY RECCONAISSANCE AND SURVEILLANCE
Milky Way
Milky Way Galaxy
Mill, John Stuart (1806-1873)
Miller, Stanley Lloyd (1930-2007)
Miller-Urey Experiment
millibar (mb)
million
Millis drives
millisecond pulsar
Milne, Edward Arthur (1896-1950)
Milstar (Military Strategic and Tactical Relay satellite)
Mimas
Mimosa (Beta Crucis)
mind
mind transfer
mind-meld
mineral
mineralocorticoid
minimal prime
minimal surface
MiniSat
Minitrack
Minkowski, Hermann (1864-1909)
Minkowski, Rudolph Leo Bernhard (1895-1976)
Minkowski space
Minkowski's Object (Arp 133)
minor axis
minor planet
Minor Planet Center (MPC)
Minotaur (rocket)
Mintaka
Miocene epoch
Mir
Mira
Mira variable
Mirach (Beta Andromedae)
Mirach's Ghost (NGC 404)
Miranda
Miranda (UK satellite)
Mirfak (Alpha Persei)
MIRLIN
mirror
mirror matter
mirror reversal problem
Mirzam (Beta Canis Majoris)
Mishin, Vasily (1917-)
missile
missing dollar problem
missing mass
mission control center
Mission of Gravity
Mission of Opportunity (MO)
mission profile
mission specialist
Mississippi Test Facility
Mitchell, Edgar Dean (1930-)
mitochondria
mitochondrial DNA
mitosis
mitotic spindle
mitral valve
mitral valve prolapse
Mittag-Leffler, (Magnus) Gösta (1846-1927)
mixed strategy
mixture
Mizar (Zeta Ursae Majoris)
m.k.s. units
MMT
MOA
Möbius band
mode
model of computation
model theory
moderator
modulation
module
modulo
Moffett Federal Airfield
Mogul, Project
Mohs scale
Moiré pattern
molar mass
molecular cloud
molecular formula
molecular quantum computing cloud
molecular weight
molecule
molecules, in space
mollusc
Molniya
Molniya launch vehicle
Molniya-type orbit
moment
moment of inertia
momentum
monazite
Monge, Gaspard (1746-1818)
monism
monkey
monkeys and typewriters
Monoceros (constellation)
monochromatic
monochromatic triangle
monocotyledon
monocyte
Monod, Jacques (1910-1976)
monoecious
Monogem Ring
monomer
monomial
monopropellant
monosaccharides
monosomy
monotonic
Monster group
Monstrous Moonshine conjecture
Monte Carlo method
Montgolfier brothers
month
Montlivault, Sales-Guyon de
montmorillonite
Montucla, Jean Etienne (1725-1799)
Monty Hall problem
MOON
Moon
Moon, communication with
Moon, future manned missions
Moon, life
MOON, MANNED MISSIONS
MOON, UNMANNED MISSIONS
Moon, voyages
Moon, water
Moon base
"Moon Hoax"
"Moon trees"
moonquake
moons, atmospheres of
moons, life on
MOP
Mopra Telescope
moraine
mordant
Morelos
Moreton wave
Morgan, William Wilson (1906-1994)
Morgan-Keenan classification
MORL (Manned Orbiting Research Laboratory)
Morley's miracle
Mormonism
Morokweng crater
morphine
morphogenesis
Morrison, Philip (1915-)
Morrison-Cocconi Conjecture
Morrison's radioglyph scheme
morula
MOS (Marine Observation Satellite)
moss
MOST (Microvariability and Oscillations of Stars)
motor
motor chamber
Moulton, Forest Ray (1872-1952)
Mount Graham International Observatory (MGIO)
Mount Hopkins Observatory
Mount Palomar Observatory
Mount Stromlo and Siding Spring Observatory
Mount Wilson magnetic classification (of sunspots)
Mount Wilson Observatory
mountain
mounting
MOUSE (Minimum Orbital Unmanned Satellite of the Earth)
mouse model
mouth
moving cluster
moving sofa problem
MPD thruster
MPS Project
MRI (magnetic resonance imaging)
mRNA
Mrs. Perkins' quilt
MS star
MSETI
MSX (Midcourse Space Experiment)
M-theory
MTI (Multispectral Thermal Imager)
Mu Arae
mucigel
mucous membrane
mucus
mud volcano
Muller, H. J.
Müller, Johann (1436-1476)
Müller-Lyer illusion
multicellular
Multichannel Astrometric Photometer (MAP)
Multichannel Astrometric Photometer and Spectrometer (MAPS)
Multi-Channel Spectrum Analyzer (MCSA)
multigrade
multiple
Multiple Mirror Telescope (MMT)
multiple myeloma
multiple sclerosis
multiple star
multiplet
multiplexing
multiplication
multipropellant
Multi-Purpose Logistics Modules
multiringed basin
multistage ignition
multistage rocket
multiverse
mumps
Munin
muon
muonium
Murasaki 312
Muratori (14th century)
Murchison meteorite
Muroc Army Air Field
Murray, Bruce C. (1932-)
Murray meteorite
Musca (constellation)
muscle
muscle operation and contraction by nerves
muscular dystrophy
muscular system
MUSES series
MUSES-C
Musgrave, (Franklin) Story (1935-)
Musson
mutant
MUSTARD (Multi-Unit Space Transport and Recovery Device)
Musudan
mutation
MX-324
My Favorite Martian
myalgic encephalomyelitis (ME)
myasthenia gravis
mycelium
mycorrhiza
Mydorge, Claude (1585-1647)
myelin
Mylar
myocarditis
myoglobin
Myojo
myometrium
myopia (near-sightedness)
myosin
myriad
myriapod
MYTHS AND LEGENDS