Galaxy

Galaxy Galaxies are a collection of stars held by gravity. They can contain trillion's of stars spanding hundred's of light years. The cartwheel galaxy was hit by another galaxy 300 million years ago. All galaxies come in different shapes and sizes. A third of galaxies are spiral spinning in the universe like catherine wheels. When new galaxies are discovered, they are called island universes. When two galaxies past too close each other, they will collide. All galaxies travel millions of kilometers per hour. Scientist still not understand how galaxies formed from the dark void of fog that was the early universe.