20 terms

Chapter 19 Stars, Galaxies and the Universe

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spectrum
the band of color produced when white light passes through a prism
light-year
the distance that light travels in one year; about 9.5 trillion kilometers
parallax
an apparent shift in the position of an object when viewed from different locations
apparent magnitude
the brightness of a star as seen from the Earth
absolute magnitude
the brightness that a star would have at a distance of 32.6 light-years from Earth
red giant
a large, reddish star late in the life cycle
white dwarf
a small, hot, dim star that is the leftover center of an old star
H-R diagram
Hertzsprung-Russell diagram, a graph that shows the relationship between a star's surface temperature and absolute magnitude
main sequence
the location on the H-R diagram where most stars lie
supernova
a gigantic explosion in which a massive star collapses and throws its outer layers into space
neutron star
a star that has collapsed under gravity to the point that the electrons and protons have smashed together to form neutrons
pulsar
a rapidly spinning neutron star that emits rapid pulses of radio and optical energy
black hole
an object so massive and dense that even light cannot escape its gravity
galaxy
a collection of stars, dust, and gas bound together by gravity
nebula
a large cloud of dust and gas in interstellar space; a region in space where stars are born or where stars explode at the end of their lives
globular cluster
a tight group of stars that looks like a ball and contains up to 1 million stars
open cluster
a group of stars that are close together relative to surrounding stars
quasar
a very luminous, starlike object that generates energy at a high rate; quasars are thought to be the most distant objects in the universe
cosmology
the study of the origin, properties, processes and evolution of the universe
big bang theory
the theory that states the universe began with a tremendous explosion 13.7 billion years ago