Astrophysics Basic Terms
singularity
point of infinite mass and infinite density in an infinitely small space, usually in a black hole
light year
9.46073047 x 10^15 meters
planet
An astronomical object orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighboring region of planetesimals.
galaxy
A gravitationally bound system of stars, stellar remnants, interstellar gas, dust, and dark matter. Galaxies range in size from dwarfs with just a few thousand (10³) stars to giants with one hundred trillion (10¹⁴) stars, each orbiting its center of mass.
AU
Astronomical Unit- distance between the earth and the sun
E=MC^2
the theory of general relativity