Unit 2: The Universe

Front

Elliptical-shaped galaxy

Back

A galaxy shaped like a flattened ball that mostly contains older stars.

Front

Spiral-shaped galaxy

Back

A galaxy that has a bright center with curving arms that look like a pinwheel.

Front

Irregular-shaped galaxy

Back

A galaxy with no clear shape that does not fit into any category.

Front

Galactic center

Back

Rotation center of a galaxy.

Front

Galaxy

Back

A huge collection of stars, gas, and dust held together by gravity; may contain many solar systems.

Front

Milky Way galaxy

Back

The spiral-shaped galaxy that contains our solar system.

Front

Solar system

Back

A star and all the planets and other objects that orbit it.

Front

Spiral arms

Back

The long, curved bands of stars, gas, and dust that extend from the center of a spiral galaxy.

Front

Big Bang

Back

The theory that the universe originated billions of years ago in an explosion from a single point of nearly infinite energy density.

Front

Redshift

Back

The farther away a galaxy is, the more its light has to travel through the expanding universe, and the more it gets stretched. When lightwaves get longer, they appear red. So galaxies far from us or moving away from us appear red.