Interstellar Matter. Components of the interstellar medium. Significance of the interstellar medium. Resources. The constellation of Orion, the hunter, is most easily visible on a clear winter night. A row of three stars makes up his belt. Hanging from his belt is his sword, a smaller row of three fainter stars.
http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/interstellar-matter
See alsoEdit. 1  List of molecules in interstellar space. 2  Nebula. 3  Interplanetary medium - interplanetary dust. 4  Interstellar medium - interstellar dust. 5  Intergalactic medium - Intergalactic dust. 6  Local Interstellar Cloud. 7  G-Cloud.
https://en.wikipedia.org/wiki/Interstellar_cloud
Looking at the center star in the sword with a pair of binoculars or a small telescope, small fuzzy patch of interstellar gas and dust is visible, called the Orion Nebula. Space is not empty. The matter in the space between the stars is called interstellar matter or the interstellar medium. The interstellar medium consists of atoms, ions, and molecules of gas and dust grains. It is both concentrated into clouds and spread out between stars and the clouds.
http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/interstellar-matter
The interstellar medium—the space between the stars—consists of nearly empty space. It is the vacuum of the universe. It would be totally empty if not for a smattering of gas atoms and tiny solid particles—interstellar matter. On average, the interstellar matter in our region of the galaxy consists of about one atom of gas per cubic centimeter and 25 to 50 microscopic solid particles per cubic kilometer. In contrast, the air at sea level on Earth contains about 1,019 molecules of gas per cubic centimeter.
http://www.scienceclarified.com/He-In/Interstellar-Matter.html
In some regions of space, however, the concentration of interstellar matter is thousands of times greater than average. Where there is a large enough concentration of gas and particles (also called cosmic dust), clouds form. Most of the time these clouds are so thin they are invisible.
http://www.scienceclarified.com/He-In/Interstellar-Matter.html
These interstellar clouds possess a velocity higher than can be explained by the rotation of the Milky Way. By definition, these clouds must have a v lsr greater than 90 km s −1, where v lsr is the local standard rest velocity.
https://en.wikipedia.org/wiki/Interstellar_cloud
Interstellar cloud. An interstellar cloud is the generic name given to an accumulation of gas, plasma, and dust in our and other galaxies. Put differently, an interstellar cloud is a denser-than-average region of the interstellar medium. Depending on the density, size, and temperature of a given cloud, the hydrogen in it can be neutral (H I regions), ionized (H II regions) (i.e. a plasma), or molecular (molecular clouds).
https://en.wikipedia.org/wiki/Interstellar_cloud
In addition to gas, the other major component of interstellar matter is dust. Dust grains permeate the entire interstellar medium, in clouds and between them. Interstellar dust grains are usually less than a millionth of a meter in radius.
http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/interstellar-matter
Analyzing the composition of interstellar clouds is achieved by studying electromagnetic radiation that we receive from them. Large radio telescopes scan the intensity in the sky of particular frequencies of electromagnetic radiation which are characteristic of certain molecules' spectra.
https://en.wikipedia.org/wiki/Interstellar_cloud
However, astronomers do not know what makes up dark matter. Most proposals include dark matter as part of interstellar matter. For example, KEY TERMS. Dark cloud — A cloud of dust that block light from stars behind it. HI region — A cloud of neutral hydrogen. HII region — A cloud of ionized hydrogen. Interstellar medium — The matter between the stars.
http://www.encyclopedia.com/science/encyclopedias-almanacs-transcripts-and-maps/interstellar-matter
what is a cloud of interstellar matter
An interstellar cloud is the generic name given to an accumulation of gas, plasma, and dust in our and other galaxies.