1. The Big Picture

2. Cosmology (another name for Astronomy) Study of the universe, including its current nature, origin, and evolution, based on observation and the use of theoretical models.

3. Sizes This is the order from largest to smallest: Largest Universe Quasars Galaxies SmallestSolar System

4. Universe The Big Bang Theory - accepted as the best current model for the origin of the universe. States that the universe began in a very hot, dense state that expanded and eventually condensed into galaxies.

5. Quasars Quasars are massive objects and act as galactic nuclei. They are the brightest objects in the universe.

6. Galaxies Galaxies form from quasars by gravity. Gravity helps condense the quasars.

7. Galaxies A galaxy is a collection of millions or billions of stars, so each galaxy is essentially a huge group of stars. We live in the Milky Way Galaxy. Three kinds of galaxies - spiral, elliptical and irregular.

8. Spiral Galaxies Spiral Galaxies are spiral in shape. They have a central nucleus with arms extending out from it. Milky Way Galaxy – OURS!

9. Elliptical Galaxies Elliptical Galaxies are similar in shape to a spiral galaxy, except they don’t have the spiraling arms coming out of the nucleus. Shape depends on the fastest moving stars within the galaxy.

10. Irregular Galaxies Irregular Galaxies do not have a definite shape to them. Therefore, they do not fit into either the spiral or elliptical galaxy category.

11. Solar System A solar system is a star and anything that orbits that star. The Solar Nebular Theory is the currently accepted idea for the origin of the solar system. It explains that the planets formed through the condensing of clouds.

12. Misc. Information Cosmic Background Radiation is persistent noise that was discovered in 1964 that is caused by weak radiation from all directions in space.

13. Misc. Info Hubble Constant is a value stating the approximate speed of galaxies moving away from Earth. The value is 70 km per second per megaparsec. The Active Galactic Nucleus is the gigantic formation of clusters of galaxies hundreds of millions of light years in size.