absolute magnitude
a brightness scale used to measure of how bright a star would be if it were seen from a standard distance
apparent magnitude
the brightness of a star as seen from earth
galaxy
a large collection of stars, dust, and gas bound together by gravity
H-R Diagram
Hertzsprung-Russell’s diagram, a graph that shows the relationship between a stars surface temperature and absolute magnitude
light-year
Light-year is the distance light travels in one year, about 9.46 trillion kilometers
luminosity
the actual brightness of an object, such as a star.
main sequence
the region of H-R Diagram where stars spend the most of their lives; it has a diagonal pattern.
nebula
a large cloud of dust and gas in interstellar space, a region in space where stars are born.
neutron star
the core of a supernova that had collapsed under gravity to the point that the electron and protons have smashed together to form neutrons.
planet
a relatively large spherical body that orbits a star
pulsar
a highly magnetized, rotating neutron star that emits a beam of electromagnetic radiation
revolution
the motion of a body that travels around another body in space; one trip along orbit
rotation
the spin of a body on its axis
star
a large celestial body that is composed of gas that emits light; the sun is a typical star.
wavelength
the distance between two adjacent troughs or crests of a wave.
supernova
a gigantic explosion in which a massive star throws its outer layer into space, but its core remains.
universe
space and all the matter and energy in it.
white dwarf
the hot, dense, dim core of matter that remains from the collapse of the low-mass star.
spiral galaxy
a galaxy shaped like a pinwheel, with a bulge in the center and spiral arms extending outwards
elliptical galaxy
a spherical or elongated galaxy with a bright center and very little dust or gas.
irregular galaxy
a galaxy with a irregular shape that does not fit any other category
electromagnetic spectrum
all of the different wavelengths and frequencies of electromagnetic radiation, from radio waves to gamma raves.
big bang theory
the theory that all matter and energy in the universe was compressed into a extremely small volume 13 billion to 15 billion years ago exploded and began expanding in all different directions
cosmic microwave background
CMB; the electromagnetic radiation leftover from the formation of the universe
