Glossary -- B

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Big Bang

a theory of the creation of the universe from an ultra-compact volume with very high temperatures about 15 billion years ago. The ultra-compact volume began expanding and is responsible for the expanding motion we see today.

black hole

the collapsed core for the most massive stars. Formed from the total collapse of a core greater than 3 solar masses to an infinitesimal point of infinite density. Gravity in the region surrounding the collapsed core is so strong that the escape velocity is greater than the speed of light. Far beyond that region, black holes obey Newton's law of gravity.

blueshift

the shift of spectral lines from an object to shorter wavelengths because the object is moving toward the observer. The greater the speed of the object, the greater the blueshift will be.

brown dwarf

object formed from the gravitational collapse of a gas cloud just as a star is but having too little mass (less than 0.08 solar masses) to undergo nuclear fusion reactions.

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last update: 06 August 1999