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the branch of astrophysics that studies the origin and evolution and structure of the universe
space object made of dust and rock particles mixed with frozen water, methane, and ammonia that forms a bright coma as it approaches the Sun
any of numerous small celestial bodies composed of rock and metal that move around the sun (mainly between the orbits of Mars and Jupiter)
stony or metallic object that is the remains of a meteoroid that has reached the earth's surface
a region of the solar system that is just beyond the orbit of neptune and that contains small bodies made mostly of ice
final stage in the evolution of a very massive star, where the core's mass collapses to a point that its gravity is so strong that not even light can escape
a "quasi-stellar" object; a starlike source of light that is extremely far away; one of the most powerful sources of energy in the universe
late stage in the life cycle of a comparatively low-mass main sequence star; formed when its core depletes its helium and its outer layers escape into space, leaving behind a hot, dense core
a very large old reddish star that is greatly expanded and cooled as its fuel has begun to run out;
A mysterious force that appears to be causing the expansion of the universe to accelerate
Unseen matter that may make up more than ninety percent of the universe. As the name implies, it does not interact with light or other electromagnetic radiation, so it cannot be seen directly, but can be detected by measuring its gravitational effects. It is believed that it was instrumental in forming galaxies in the Big Bang.
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