Celestial Bodies Flashcards
Spiral Galaxy
Shaped like… a spiral! (Imagine water going down a drain) They usually have two arms but may have more. Usually made up of younger stars and many globular clusters. The Milky Way is a spiral galaxy.
Elliptical Galaxy
Spherical shaped and may be larger than spiral galaxies. Usually filled with older stars and open clusters.
Irregular Galaxy
A galaxy that does not fall into one of the other two classifications. This is usually due to interactions with other stellar objects, such as a collision between two galaxies.
Quasar
The most distantly observed and luminous objects in the universe. According to their high redshift, we know they are the most distant objects observed. The fact that they are observable at all from this distance points to their extreme luminosity. One quasar has the luminosity equivalent to a trillion suns. Astronomers believe they are the result of supermassive black holes in the center of some of the earliest formed galaxies in the universe.
Supermassive Black Hole
It is believed there is one of these in the middle of the Milky Way and most other galaxies, forming the gravitational center that the other stars in the galaxy revolve around.
Galaxy Groups
A large group of galaxies (usually at least 50) which are gravitationally connected.
Galaxy Clusters
Larger than a Galaxy Group. Usually has between 50 and 1,000 galaxies in each cluster. Think about that one for a minute – 1,000 galaxies each containing billions and trillions of stars!
Local Cluster
The collection of galaxies in which our own Milky Way is a part of. It numbers roughly 53 galaxies with the Milky Way and the Andromeda Galaxy being two of the largest.
Galaxy
A group of stars and stellar matter held together by gravitational forces. Can contain anywhere from 10 million to 100 trillion stars. They are usually classified by their shape. The primary types are Spiral, Elliptical, and Irregular.
