![]() ![]() Therefore, objects orbiting far from the center of the galaxy should move slower than objects closer to the center, just like the planets in our solar system. If we assume that the bright part of a galaxy shows where most of the mass is, then most of the mass is near the center, and at the dim edge of a galaxy there should not be much mass. We can apply a similar analogy to galaxies. This is because there is less gravitational pull from the sun on planets farther out and, to keep from spiraling into or away from the sun, they must move slower. As the distance from the sun increases, the speed at which planets move decreases. The innermost planets like Mercury and Venus orbit the sun the fastest. In our solar system, almost all of the mass is in the sun. The first type of evidence supporting the existence of dark matter has to do with the way dark matter affects the movement of celestial bodies. Dark Matter Affects the Movement of Stars Within Galaxies This means that there is four times more dark matter compared to regular matter! If dark matter is so difficult to observe, why do scientists believe it actually exists? The evidence to support the existence of dark matter is extensive, and we will explore three main examples in the following sections. We know that dark matter makes up ~80% of the total mass of galaxies. ![]() However, they know what dark matter is not, by observing the way it behaves compared to other materials. ![]() Astrophysicists are still unsure what dark matter is, exactly. Scientists know that dark matter does not emit light from any part of the electro-magnetic spectrum, but dark matter has been observed to be influenced by gravity. Some scientists, specifically astrophysicists, spend a great deal of time generating theories about what dark matter could be. This unique property makes it impossible to observe these types of matter, so scientists call it dark matter. Yet, there is matter in the universe that does not emit light in any part of the electro-magnetic spectrum, which means that we cannot observe it with our telescopes. They can even use some of this information to understand the laws of the universe. Scientists use the various wavelengths of detected light to determine key information about our universe’s celestial bodies, such as distance away, age, size, and shape. In fact, one super telescope you may have heard of, the Hubble telescope, can see more than 13.4 billion light years away ! All telescopes work by detecting light in the electro-magnetic spectrum, from visible light to X-rays, emitted by these celestial bodies. Some telescopes can detect light from millions of light years away. With the help of different kinds of telescopes, we can observe these celestial bodies through the light they radiate. These objects make up all the light-emitting matter in the universe. These bright celestial bodies include planets in our solar system, stars in our galaxy, and entire galaxies that are far, far away. When we look up into the night sky, we notice that it is filled with thousands of stars. In this article, we will discuss how scientists use science and observations from telescopes to predict the existence of dark matter and why scientists think it pervades every corner of our universe. How do we even know that such a thing exists? The greatest challenge for studying dark matter is that we cannot see it. There are many theories about what dark matter could be, but we have yet to understand its true nature. Understanding the existence and make-up of a mysterious substance called dark matter is one of the leading challenges scientists face today. There is still a lot we do not know about the universe. ![]()
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