Dictionary
 Astronomical Unit= Measures distance. The distance between the Earth and sun is one astronomical unit, or about 92 million miles.
Black Hole= a rare object created when a star over a certain mass dies. In the resulting supernova, the core is compressed so much and it's gravity is so strong that even light can't escape it's gravitational pull. A typical black hole has 4 or more solar masses, and is about the size of a small city.
Cosmic Rays= highly energetic particles that originate from deep space. They are usually electrons, protons, or neutrons, but don't have to be. Most are thought to be energized by supernova or other explosive phenomenon, but some are even more energetic than is thought possible.
Drake Equation= Created by Astronomer Francis Drake, the Drake equation attempts to calculate the number of alien civilizations that exist in the world, using a variety of numbers.
Electron Degeneracy Pressure= what prevents gravity from pulling non-fusing star cores and white dwarves from becoming a black hole. Since electrons have the same charge, they repel each other. In an object that is held up by degeneracy pressure, their atoms are so close, only the repulsiveness from their electrons keeps them apart.
Galaxies= Galaxies are large groups of stars nebulae and other objects that orbit the galactic center.
Light Year= A unit that measures distance in astronomy. 1 light year is the distance light travels in a year, or roughly 5.8 trillion miles. If you want to get more digits than that, calculate it out, light travels 186,282.4 miles per second.
Nebula= A large cloud of dust and gas floating in space.
Neutrino= A very small particle produced in large numbers in stellar cores, believed to account for some of the missing mass in the universe.
Neutron Star= When a large star dies, depending on it's mass, a neutron star will be left over. Neutron stars are composed nearly entirely of neutrons, which are compacted to densities of millions of tons per cubic inch.
Pulsars= are a type of neutron star. What sets them apart is that they act like lighthouses, they let out 2 huge beams of radiation, one from each pole, which are detectable across the galaxy.
Planetary Nebula= A large nebula ejected from a low mass star as it dies. It was given the name planetary nebula because when they were first discovered, they thought it was a planet forming cloud surrounding a young star.
Quasars= Quasars are theorized to be in the center of all regular galaxies. They are thought to be large black holes, up to a few billion solar masses, surrounded by large clouds of dust and gas.
Scarps= Ridges that exist on some planets. They are formed as the planet cools and shrinks, and the crust is forced over itself.
Solar System= A system consisting of a star and the planets that orbit it.
Solar Mass= a unit that measures the mass of celestial objects. The sun weighs one solar mass
Super Nova= An immense explosion created by the death of a large star.
W.I.M.P.'s= weakly interacting massive particles, one of the explanations for the missing mass in the universe.
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