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interstellar matter

(Encyclopedia)interstellar matter, matter in a galaxy between the stars, known also as the interstellar medium. The interstellar gas, which constitutes about 99% of the interstellar matter, consists mostly of hyd...

matter

(Encyclopedia)matter, anything that has mass and occupies space. Matter is sometimes called koinomatter (Gr. koinos=common) to distinguish it from antimatter, or matter composed of antiparticles. The atomic th...

phases of matter

(Encyclopedia)phases of matter: see states of matter. ...

states of matter

(Encyclopedia)states of matter, forms of matter differing in several properties because of differences in the motions and forces of the molecules (or atoms, ions, or elementary particles) of which they are composed...

gray matter

(Encyclopedia)gray matter: see nervous system. ...

dark matter

(Encyclopedia)dark matter, material that is believed to make up nearly 27% of the mass of the universe but is not readily visible because it neither emits nor reflects electromagnetic radiation, such as light or ra...

decay of organic matter

(Encyclopedia)decay of organic matter or putrefaction, process whereby heterotrophic organisms, including some bacteria, fungi, saprophytic plants, and lower animals, utilize the remains of once-living tissue as a ...

McDonald Observatory

(Encyclopedia)McDonald Observatory, astronomical observatory located on Mt. Locke, near Fort Davis, Tex.; founded in 1932, sponsored by the Univ. of Texas in cooperation with the Univ. of Chicago. Its equipment inc...

Black Lives Matter

(Encyclopedia)Black Lives Matter, a global political movement. Founded in 2013 by organizers Alicia Garza, Patrisse Cullors, and Opal Tometi, the #Black Lives Matter ...

Horsehead Nebula

(Encyclopedia)Horsehead Nebula, dark nebula located in the constellation Orion; designated IC 434 or B 33. It consists of a cloud of nonluminous interstellar matter resembling the outline of a horse's head and appe...