Dark Matter
Most of the mass-energy, about 95%, in the universe is 'dark'. By dark we mean that it does not emit any form of electromagnetic radiation. The existence of Dark Matter is inferred indirectly by its gravitational effect.
Dark Matter
Matter that produces no detectable energy, but that reveals its presence through its gravitational pull on the visible matter around it. Dark matter comprises more than 90 percent of all the matter in the universe.
Dark Matter
Related Category: Astronomy: General
material that is believed to make up (along with dark energy) more than 90% of the mass of the universe but is not readily visible because it neither emits nor reflects electromagnetic radiation, ...
Dark matter inversion
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History
A dark matter inversion is a dark matter phenomenon not particularly similar to wormholes.
Dark matter
This refers to the cosmological use of the term. For other uses, see Dark matter (disambiguation) ...
dark matter
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Dark Matter:
Numerous candidates for the dark matter component in the halos of galaxies and clusters of galaxies have been proposed over the years, but no successful detection of any of them has yet occurred.
Dark Matter should not to be confused with Dark Energy, Dark Fluid (is an alternative theory to both Dark Matter and Dark Energy and attempts to explain both phenomena in a single framework), ...
Dark matter also plays a role in the early universe. Astronomers theorize that the presence of dark matter helps to explain the relative amounts of light elements and isotopes produced in the Big Bang.
Dark Matter
Portions of this entry contributed by Stewart Scanlon
An object can be detected in one of two ways: either by observing it directly, or observing the effects it has on other objects.
Definition: Dark Matter: Name given to the amount of mass whose existence is deduced from the analysis of galaxy rotation curves but which until now, has escaped all detections. There are many theories on what dark matter could be.
Dark matter
Wikipedia, the free encyclopedia - Cite This Source
In astrophysics and cosmology, dark matter is hypothetical matter of unknown composition that does not emit or reflect enough electromagnetic radiation to be observed directly, ...
Dark Matter
I can't believe it!
Dark matter was initially called "missing matter" because astronomers could not find it by observing the Universe in any part of the electromagnetic spectrum.
Seeing dark matter for the first time
Astronomers have used the Very Large Telescope (VLT) and the Hubble Space Telescope (HST) to directly image and obtain a spectrum from a dark matter object for the first time, ...
Dark Matter
It is widely accepted that there are vast amounts of unseen material in the universe, perhaps 10 times as much as in detectable galaxies and intergalactic gas. What is the evidence?
Dark matter has been a puzzle at the forefront of cosmology since the 1970s, ...
Dark matter is virtually transparent to everything. You could walk right through a patio door made out of dark matter and you wouldn't even feel it.
Many astronomers now believe that the mass of invisible "dark matter" may outweigh all other kinds in the universe, and that its attraction may be a major cause of the existence of galaxies.
Some have suggested that interactions between normal and dark matter could spread out the dark matter, but current simulations don't indicate that this happens in dwarf galaxies.
Dark Matter
(a) Material astronomers cannot see but whose presence they believe in either because they detect its gravitational influence or because certain theories predict its existence.
DARK MATTER - Form of matter that does not emit light, absorb light, or otherwise interact with electromagnetic radiation.
DARK MATTER
Fortunately for cosmology, the fact that most of the universe is made of dark matter, which has properties very different from those of normal matter, provides an alternative explanation for the large-scale structure we see today.
DARK MATTER, COSMOLOGICAL
Edmund Bertschinger
Dark matter is mass that does not emit or reflect detectable electromagnetic radiation, yet is detectable by its gravitational effect on other, luminous, matter.
dark matter halo
An estimate of the mass of a galaxy is obtained by measuring the rotation speed of parts of the galaxy and applying a simple dynamical argument based on Newton's laws of motion.
dark matter Term used to describe the mass in galaxies and clusters whose existence we infer from rotation curves and other techniques, but which has not been confirmed by observations at any electromagnetic wavelength.
dark matter
matter that exerts gravitational force but does not emit any detectable light or radiation; dark matter comprises most of the mass of the universe but its exact nature remains unknown
dark nebula ...
Dark Matter: Any nonluminous astronomical object or particle that is detected only by its gravitational influence.
Dark matter- invisible matter that is believed to make up 99% of the mass of the universe
Declination- the angular distance of a celestial object north or south of the celestial equator; it corresponds to latitude on the Earth ...
Dark Matter
a term used to describe matter in the universe that cannot be seen, but can be detected by its gravitational effects on other bodies.
Declination
the angular distance of an object in the sky from the celestial equator.
dark matter: Nonluminous material that is detected only by its gravitational influence.
dark nebula: A nonluminous cloud of gas and dust visible because it blocks light from more distant stars and nebulae.
Dark Matter - Matter that cannot be detected or has not yet been detected by the radiation it emits. The presence of dark matter can be deduced from its gravitational interaction with other bodies ...
Dark matter
During the 1970s, observations were made that - assuming that all of the matter within the universe could be seen - created problems for the Big Bang theory, ...
Hot dark matter is a hypothetical form of dark matter which consists of particles that travel with ultrarelativistic velocities. The best candidate for the identity of hot dark matter is the neutrino....
DARK MATTER
Dark matter is unknown matter that may constitute as much as 99 percent of the matter in the universe.
D'ARREST, H.L.
Heinrich Louis d'Arrest (1822-1875) was a Danish astronomer and the co-discoverer of (in 1846), with .
Dark Matter
Matter that is too dim to be detected by telescopes. Astronomers infer its existence by measuring its gravitational influence. Dark matter makes up most of the total mass of the universe.
Flat Universe ...
Dark Matter exists on all scales
Galaxy Evolution
study distant (therefore younger) galaxies
star formation, chemical enrichment, gas dispersal
? early times; top down or bottom up ?
A dark matter map was published at the beginning of 2007 that probed the dark matter distribution over a large expanse of sky and depth (distance---see the "Dark matter map" figure below).
[10.2] COSMIC DARK MATTER / DARK ENERGY / MULTIVERSE THEORIES
[10.3] TO THE EDGE OF THE UNIVERSE
[10.4] COMMENTS, SOURCES, & REVISION HISTORY ...
Tom van Flandern: "Dark Matter, Missing Planets & New Comets. Paradoxes resolved, origins illuminated", North Atlantic Books 1993, ISBN 1-55643-155-4 ...
It is designed to detect dark matter, antimatter, and matter not previously detected in the universe.
Dark Matter Galaxy
Solar System Galaxy Universe
The Closest Galaxy to the Milky Way
The Diameters of the Milky Way
How Many Stars are in the Milky Way?
How Many Stars are in Galaxies?
How Many Planets are in the Milky Way?
If most of the stuff that is out there is dark matter, what is it? What stuff can be so abundant, yet remain undetectable? There are two main ideas as to what type of stuff comprises the dark matter.
Micrometeor impacts could kick dark matter off Phoebe which is then swept up by Iapetus.
Much of this invisible dark matter, which astronomers call "missing mass", could be made up of brown-dwarfs. Our universe is currently expanding, due to the Big Bang.
We call them dark matters. They reveal their existence by their gravity. How fast an object revolves depends on how much matter inside its orbit.
Scientists have proposed the existence of "dark matter" halos around individual galaxies and clusters of galaxies.
What evidence is there for "dark matter" in galaxy clusters?
Why don't spiral arms get all wound up tightly in spiral galaxies?
What is a Standard Candle? What are some of the standard candles, and under what circumstances is each one useful?
Dark matter is woven in and out of the surrounding gases. It is surmised that eventually the gases will coalesce, producing either a new star or perhaps even a whole new system of sun and planets, similar to our own.
Current mass estimates for the Andromeda halo (including dark matter) give a value of approximately 1.23 M☉ (or 1.2 million million solar masses) compared to 1.9 M☉ for the Milky Way.
The first mention of this so-called dark matter was by Franz Zwicky in 1933.
GLOSSARY What is dark matter? How long is a light-year? Have you ridden a galactic plane? Can you fill in a coronal hole? Look up these and other astronomical terms.
ADDITIONAL RESOURCES external links ...
Scientists have been thinking about a variety of causes, such as the gravitational attraction of planets or even unknown dark matter; radiation pressure when photons hit the spacecraft; interaction between the solar wind and the spacecraft; ...
The blue field of planets, stars and galaxies stands for the universe. The black background represents dark energy and dark matter in space.
MACHO
MACHO stands for Massive Compact Halo Object. MACHOs are objects that could account for some (or all) of the dark matter in the halos of galaxies, like white dwarfs, neutron stars, and black holes.
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Axions would be able efficiently to transport energy out of stars or out of supernova cores. They have also become candidates to explain cold dark matter.
Cosmologists theorize that "dark matter," a hypothetical material that neither radiates nor reflects light, has sufficient mass to generate the gravitational fields responsible for the heterogeneous structure of the universe.
mass are observed in keplerian orbits with periods as short as 15.2 years. This spiral disk that we call the Milky Way includes some 200 billion stars, thousands of gigantic clouds of gas and dust, and enormous quantities of mysterious dark matter.
While some of these cool, dim objects were born in the Milky Way's disk like Sol, the oldest ones may be a major constituent of the galaxy's halo. Indeed, some astronomers believe that around 10 percent of the local dark matter halo may be in the ...
 See also: Universe, Galaxies, Galaxy, Light, Mass
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