- the distance light travels in one year.
- made up of a cluster of stars. Shapes are disk irregular, and elliptical.
Big Bang Theory
- states that all galaxies are originated from one huge mass of densely packed matter.
- a shift toward longer wavelengths of the spectral lines emitted by a celestial object that is caused by the object moving away from the earth.
- all matter and energy that exists in space.
- a star is a massive, luminous ball of plasma held together by gravity. The nearest star to Earth is the Sun, which is the source of most of the energy on the Earth.
- a cloud in outer space consisting of gas or dust that forms after a star explodes.
Herztsprung-Russell Diagram (H-R Diagram)
- two astronomers plotted the data of stars on a chart according to their surface temperature and brightness.
- a medium-sized star near the edge of a disk-shaped galaxy.
- another word for brightness.