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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...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...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...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...plasma
(Encyclopedia)plasma, in physics, fully ionized gas of low density, containing approximately equal numbers of positive and negative ions (see electron and ion). It is electrically conductive and is affected by magn...brown dwarf
(Encyclopedia)brown dwarf, in astronomy, celestial body that is larger than a planet but does not have sufficient mass to convert hydrogen into helium via nuclear fusion as stars do. Also called “failed stars,”...ultraviolet astronomy
(Encyclopedia)ultraviolet astronomy, study of celestial objects by means of the ultraviolet radiation they emit, in the wavelength range from about 90 to about 350 nanometers. Ultraviolet (UV) line spectrum measure...Herzberg, Gerhard
(Encyclopedia)Herzberg, Gerhard gĕrˈhärt hûrtsˈbûrg [key], 1904–99, Canadian physicist, b. Hamburg, Germany. He studied at Darmstadt, Göttingen, and Bristol, England, receiving a doctorate in engineering p...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...Struve
(Encyclopedia)Struve shtro͞oˈvə [key], family of astronomers. Friedrich Georg Wilhelm von Struve, 1793–1864, was born in Germany but later lived in Russia. While director (1817–39) of Dorpat Observatory he w...Browse by Subject
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