2.  The universe is everything throughout space.  The universe is constantly changing. It is being created and destroyed all of the time.  There are many theories on how the universe was created.

3.  A galaxy is a collection of dust, gas and other celestial bodies (planets, stars, asteroids, comets, etc) these are all bound together by gravitational pull.  The universe is made up of three different types of galaxies.  Spiral  Elliptical  Irregular

4.  A spiral galaxy is one with spiral arms. The arms extend out from the center of the galaxy.  The arms consist of bright stars, dust, and gas.

5.  There are two different types of spiral galaxies:  Normal- these have arms that extend in a spiral motion from the center of the galaxy  Barred- these have arms which extend from a large bar of stars and gas that pass through the center of the galaxy.

6.  An elliptical galaxy is shaped like large three dimensional ellipses.  Many of them are football shaped while others are round  These galaxies have no arms.

7.  An irregular galaxy is one without rotational symmetry.  Many galaxies are placed into this category since they don’t fit into either of the other.

8.  The milky way is the spiral galaxy where we live which might contain up to one trillion stars.

9.  It contains the Earth, Sun, Moon, and many other celestial bodies that we are familiar with.  Our solar system is located on the outer edge of the galaxy.  At the center of the milky way there is a massive black hole, which some scientist believe to be 2.5 million times as large as the sun.

10.  The solar system consists of eight planets, moons, stars, the sun, and many other celestial bodies.  The center of the solar system is the sun.  The gravitational pull from the sun keeps all eight planets in their own orbit.