Coma Galaxy Cluster

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Coma Cluster. Image Credit: NASA, ESA, Hubble Heritage Team
Challenge: Coma Cluster: In our Milky Way Galaxy, star clusters are quite common. Almost all stars start out in one, and these clusters come in many shapes in sizes. Some are more diffuse while some are very tight with hundreds of thousands of stars packed into just a few light years. But star clusters are not the only type of cluster. In fact, our giant island of gas and dust that is the Milky Way is part of one such cluster. These clusters are known as galaxy clusters, the largest type of object in the universe. These clusters are diverse, just like star clusters, and can be small with just a couple of galaxies, or be large with over 10,000 galaxies. The Coma Cluster of galaxies is one of the far larger clusters and is extremely dense. At a distance of around 320 million light years away, the Coma cluster is only 20 million light years across. This high density of galaxies ensures that there are many collisions between galaxies, creating a large number of elliptical galaxies. Since the galaxies are all gravitationally bound, they don’t ever wander too far from the cluster and end up pulling into each other all the time. These collisions destroy any spiral structures these galaxies may have and shapes them into giant flat discs that are known as elliptical galaxies. The Coma Cluster has a few spiral galaxies left, and they owe their existence to their location on the outskirts of the cluster. In the outskirts, galaxies are far less likely to collide and therefore are far safer from being transformed into an elliptical. Seeing the Coma Cluster is a rewarding challenge that requires a medium to large sized telescope and dark skies. To find the cluster look to the constellation Coma Berenices between Leo and the familiar shape of the Big Dipper. Coma Berenices itself is rather dim and will appear as an L shape in the sky. Inside of this L is where the galaxy cluster can be found. It is unlikely you’ll be able to see even the brightest galaxy in a finder scope or binoculars in even moderately light polluted areas, so you’ll have to scan the area with your telescope itself. You’ll know you’ve struck gold when you see fuzzy patches of light in your eyepiece. As with all clusters stellar or galactic, the larger the aperture of your telescope, the more galaxies you’ll see.

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