Fifth Grade
Worksheets
Four Kinds of Galaxies
Caption: Picture shows two galaxies colliding. Photo credit: NASA Spitzer Space Telescope, JPL-Caltech
A galaxy is a huge group of stars, gas, and dust held together by gravity. Larger galaxies may have as many as a trillion stars. A galaxy may be one hundred thousand light years or more across. A light year is the distance that light travels in one year, about six trillion miles. Galaxies may be found alone in space or in large groups. A large group of galaxies is called a "supercluster." A supermassive black hole is thought to be at the center of every galaxy. This largest type of black hole is thought to contain millions or maybe even billions of times the mass of our sun.
Galaxies attract each other. Some of them collide. The collisions cause the birth of new stars. Galaxies come in different shapes. They are usually divided into four general shapes.
