KEY Terms

The Universe- Space and all the matter/ energy in it.

Cosmology- Study of the origin of the universe

Astronomical Unit- Average distance between Earth and the Sun (93 million miles), it takes lights 8 minutes to cover this distance.

Light Year-Distance light travels in a year. (6 trillion miles)

Edwin Hubble

• Determined that other galaxies exist besides the Milky Way.

• Observed galaxies were moving away from each other.

Hubble's Law- the farther away a galaxy is, the faster it is moving away from us (supports the big bang theory).

Big Bang Theory

- 13.8 billion years ago.
- Universe began as a small spec of dust and expanded rapidly into what we see today.
- Based on the observation galaxies are moving away from each other.

​Proves the Universe is expanding.

​More proof of the history of our Universe.

Galaxy

Large assemblage of stars (often gas and dust), typically containing billions of member stars.
Star: large hot ball of gas which generates energy.

- Around 100 billion galaxies in the universe.
- Held together by gravitational attraction of stars.
- Formed around 200 million years after the "Big Bang"

Three major types:
1.) Spiral
2.) Elliptical
3.) Irregular

Constellation

• Group of stars that form a pattern in the sky.

• Stars are far away from each other in space.

• Patterns of constellations are dynamic; therefore, the constellations of 100,000 years ago are quite different from today's.