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Astronomy Vocabulary

Unit 2 Vocabulary for Astronomy; Part 2

TermDefinition
Photosphere The luminous envelope of a star from which its light and heat radiate
Chromosphere A reddish gaseous layer immediately above the photosphere of the sun or another star; a star's outer atmosphere
Corona A rarefied gaseous envelope of the sun and other stars; crownlike shape
Solar Wind The continuous flow of charged particles from the sun
Sunspot A spot or patch appearing from time to time on the sun's surface
Prominence A stream of incandescent gas projecting above the sun's chromosphere
Solar Flare A brief eruption of intense high-energy radiation from the sun's surface
Aurora A natural electrical phenomenon characterized by the appearance of streamers of reddish or greenish light in the sky, usually near the North and South poles
Nuclear Fusion A nuclear reaction in which atomic nuclei of low atomic number fuse to form a heavier nucleus with the release of energy
Constellation A group of stars forming a recognizable pattern that is traditionally named after its apparent form or identified with a mythological figure
Binary Star A system of two stars in which one star revolves around the other or both revolve around a common center
Light-year A unit of astronomical distance equivalent to the distance that light travels in one year, which is 9.4607 × 1012 km (nearly 6 trillion miles)
Apparent Magnitude The magnitude of a celestial object as it is actually measured from the earth
Absolute Magnitude The magnitude (brightness) of a celestial object as it would be seen at a standard distance of 10 parsecs
Main-sequence Star Any star that is fusing hydrogen in its core and has a stable balance of outward pressure from core nuclear fusion and gravitational forces pushing inward
Red Giant A very large star of high luminosity and low surface temperature
Supergiant A very large star that is even brighter than a giant, often despite being relatively cool
Cepheid Variable A variable star having a regular cycle of brightness with a frequency related to its luminosity, so allowing estimation of its distance from the earth
Nova A star showing a sudden large increase in brightness and then slowly returning to its original state over a few months
Nebulae A cloud of gas and dust in outer space, visible in the night sky either as an indistinct bright patch or as a dark silhouette against other luminous matter
Hertzsprung-Russell Diagram A two-dimensional graph in which the absolute magnitudes of stars are plotted against their spectral types
Protostar A contracting mass of gas that represents an early stage in the formation of a star
Supernova A star that suddenly increases greatly in brightness because of a catastrophic explosion that ejects most of its mass
White Dwarf A small very dense star that is typically the size of a planet
Neutron Star A celestial object of very small radius and very high density, composed predominantly of closely packed neutrons
Pulsar A celestial object, thought to be a rapidly rotating neutron star, that emits regular pulses of radio waves and other electromagnetic radiation
Black Hole A region of space having a gravitational field so intense that no matter or radiation can escape
Galaxy A system of millions or billions of stars, together with gas and dust, held together by gravitational attraction
Hubble's Law A law of cosmology stating that the rate at which astronomical objects in the universe move apart from each other is proportional to their distance from each other
Big Bang Theory A theory that deduces a cataclysmic birth of the universe from the observed expansion of the universe, cosmic background radiation, abundance of the elements, and the laws of physics
Created by: gracebrown