What Does Gravity Do in a Galaxy? Home Where are we? What is a galaxy? How are galaxies formed? What is at the center of our galaxy? Dark Matter Bibliography

Elliptical Galaxy This is a picture of an early-stage galaxy before it has condensed into a disk shape. Gravity will eventually pull the matter together into a defined shape we recognize as a spiral galaxy. First the galaxy will be flattened, then it will orient itself with a spin, and finally it will develop arms and/or bars. All of this attraction between the mass present is due to gravity. Image credit: apod.nasa.gov

Galaxy on Edge Gravity plays a number of roles in a galaxy, pulling stars toward one another, flattening the collection of stars into a plane, causing stars to slingshot past one another, and the creating a spin of the entire galaxy. While it may seem as though gravity between the stars plays every role in the binding of a galaxy, calculations and simulations prove that the gravity interaction between stars and the galactic center is not enough to keep galaxies together. What a galaxy needs is more mass than we can account for. Dark matter is the solution to this baffling problem. Image Credit: apod.nasa.gov