The world we see and know is made up of normal matter. Anything made of atoms is considered normal matter. Normal matter makes up 5% of all matter. So what makes up the rest of the ninety-five percent? Dark energy makes up about seventy percent of our universe, while dark matter makes up the last twenty-five percent. What is dark matter? Dark matter is the only explanation we have for why our universe expands the way it does, but we have no idea what makes it up. Dark matter doesn't accumulate like normal matter, so it doesn't make up anything we think is as important as planets and life forms. Instead, dark matter is widespread throughout our galaxy, spanning millions of light years. The diffusion of dark matter is much more significant than normal matter, for example our Milky Way is only a few thousand light years thick and about 100,000 light years in diameter, yet that is exactly what we see, normal matter. Dark matter also extends beyond normal matter for millions of years in all directions. Both of these types of matter influence gravitation, but to what extent? The normal mass of matter, such as that of objects such as the sun, is what makes up most of the gravitational pull, dark matter is estimated to have half the effect the sun has on the earth. To really see dark matter in action you have to take a step back and look at our entire galaxy. Dark matter works in a much broader aspect. It is easier to see the effect of Dark Matter from further away because it extends beyond Normal Matter. Given the gravitational pull of Normal Matter, stars closer to the center of a galaxy should travel at a greater speed than stars farther from the center. However, in the 1970s Vera Rubin discovered that all the stars... in the center of the card... d.). Retrieved from http://science.howstuffworks.com/dictionary/astronomy-terms/dark-matter.htmChase, S. (n.d.). Retrieved from http://math.ucr.edu/home/baez/physics/Relativity/GR/dark_matter.htmlhttp://www.washingtonpost.com/blogs/innovations/wp/2013/11/07/dark-matter- what-do-we-know-and-why-should-you-care/Al-Khalili, J. (2013, November 18). How close are we to discovering dark matter? Retrieved from http://www.bbc.co.uk/news/science-environment-24987749http://www.seasky.org/celestial-objects/dark-matter.htmlRubin, V. (n.d.). Retrieved from http://www.indiana.edu/~geol105/images/gaia_chapter_1/dark_matter_in_the_universe.htmhttp://www.learner.org/courses/physics/unit/text.html?unit=10&secNum=2Charles, C. ( n.d.). Retrieved from http://www.huffingtonpost.com/2013/12/08/dark-matter-black-holes_n_4408646.htmlhttp://space.about.com/od/deepspace/a/What-Is-Dark-Matter. htm