Stars, Galaxies and Universe
Science

States that the universe began with a huge explosion 13.8 billion years ago
Big bang theory
States that the universe began with a huge explosion 13.8 billion years ago. Big Bang Theory. The Big Bang Theory explains how the universe started from an extremely hot and dense point and has been expanding ever since.

All the wavelengths or frequencies of electromagnetic radiation
Electromagnetic spectrum
All the wavelengths or frequencies of electromagnetic radiation. Electromagnetic spectrum. The electromagnetic spectrum is the range of all types of light, from radio waves to gamma rays, that travel through space.

A graph that plots the surface temperature of stars against their absolute brightness
Hertzsprung Russell diagram
A graph that plots the surface temperature of stars against their absolute brightness. Hertzsprung Russell diagram. It is a chart used by astronomers to classify stars and understand their evolution.

States that the farther away a galaxy is, the faster it is moving away (as the universe expands)
Hubbles law
Sure! "States that the farther away a galaxy is, the faster it is moving away as the universe expands. Hubble's law. In simple terms, Hubble's law means that the universe is expanding, with distant galaxies moving away faster than those nearby."

The distinct diagonal band on an H-R diagram that includes 90% of all stars
Main sequence
The distinct diagonal band on an H-R diagram that includes 90 of all stars main sequence. Main sequence stars are those that are in the stable phase of their lifecycle, fusing hydrogen into helium in their cores.

A dense core composed mainly of neutrons, left behind after a supernova explosion
Neutron star
A dense core composed mainly of neutrons, left behind after a supernova explosion. Neutron star. A neutron star is a super compact object formed when a massive star's core collapses under gravity after a supernova, squeezing its mass into a small, incredibly dense ball mostly made of neutrons.

A group of no more than a few thousand stars, all of which are about the same age
Open cluster
A group of no more than a few thousand stars, all of which are about the same age. Open cluster. An open cluster is a collection of stars that formed together in the same region of space and are loosely bound by gravity.

The hot dense core of a star left behind when its outer layers have escaped into space
White dwarf
The hot dense core of a star left behind when its outer layers have escaped into space. White dwarf. A white dwarf is the remains of a small or medium-sized star after it has exhausted its nuclear fuel and shed its outer layers.