Coma Cluster

A huge group of galaxies lives far away. It has over 1,000 galaxies in it. Some look like bright swirls. Many look like round blobs.

These galaxies move very fast. They move so fast they should fly apart. But they stay together. A hidden mass holds them in place. Most of this mass is dark and cannot be seen. It is a giant home in space.

The Coma Cluster is a huge group of galaxies. It has more than 1,000 galaxies in it.

This cluster lives far away in space. It is about 321 million light years from Earth. It gets its name from a group of stars called Coma Berenices.

Most galaxies in the center look like round blobs. These are called elliptical galaxies. Two very large ones sit in the middle. Their names are NGC 4874 and NGC 4889. Some galaxies in the cluster look like bright swirls. We call these spiral galaxies.

Some spiral galaxies have long tails. These tails form when a galaxy moves through other things.

In 1933, a man named Fritz Zwicky studied this cluster. He saw that the galaxies move very fast. They move too fast to stay together. He thought a hidden mass must hold them. He called this dark matter. Scientists now think dark matter makes up 90% of the cluster's mass. This invisible stuff helps keep the whole cluster together.

The Coma Cluster is a huge group of galaxies in space. It is also called Abell 1656. This group is part of a larger area called the Coma Supercluster. It sits near the Leo Cluster in the sky. The cluster gets its name from the constellation Coma Berenices.

It is very far away from our home. The mean distance to the cluster is 321 million light years. This group is a very important part of our universe.

Inside the cluster, galaxies come in different shapes. Most galaxies in the middle are elliptical galaxies. These look like round or oval blobs. Some are giant and some are dwarf galaxies. Two huge elliptical galaxies sit in the center. Their names are NGC 4874 and NGC 4889.

You can also find spiral galaxies near the edges. Some of these spirals have long tails. These tails form through a thing called ram-pressure stripping. This happens as a galaxy moves through the cluster.

People have been looking at this cluster for a long time. William Herschel first noted it in 1785. Later, Max Wolf did a photographic survey in 1901. Astronomers at Mount Palomar Observatory studied it more in the 1950s. They helped us understand how big the cluster really is.

This work helped show the full extent of the group. It is one of the first galaxy clusters ever written about in science books.

In 1933, a scientist named Fritz Zwicky studied the cluster. He noticed something very strange about how it worked. The galaxies were moving much too fast. They moved at a speed of 1000 km/s or more. He thought they should fly apart instead of staying together.

Zwicky said there must be hidden mass holding them. He called this "dunkle Materie," or dark matter. Today, we think dark matter makes up 90% of the cluster's mass.

We can also find X-rays coming from this area. An X-ray source was reported before August 1966. A satellite named Uhuru saw a strong source near the center. Scientists suggested calling this source Coma X-1.

This X-ray source is very large and spread out. It is not just one single galaxy making the light. This shows that the cluster is a very busy place. It is full of energy and hidden things we are still learning about.

The Coma Cluster, also known as Abell 1656, is a massive collection of galaxies. It is one of the most significant structures in our local universe. This cluster is a major part of the Coma Supercluster. The Leo Cluster is the other major part of that supercluster. The cluster sits within the constellation Coma Berenices.

This cluster is located at a mean distance of 99 megaparsecs from Earth. This is equal to about 321 million light years. Because it is so far away, it is quite difficult to see. However, amateur astronomers can see its ten brightest spiral galaxies. These galaxies have apparent magnitudes between 12 and 14. You can observe them using telescopes larger than 20 centimeters. The cluster is positioned near the north galactic pole in the sky.

The galaxies within the cluster have very different shapes and sizes. Most galaxies in the central region are elliptical galaxies. These can be giant ellipticals or smaller dwarf ellipticals. Two supergiant elliptical galaxies dominate the very center. Their names are NGC 4874 and NGC 4889. You can also find S0 galaxies and some spiral galaxies. Many of the younger spiral galaxies are likely near the outskirts.

Some galaxies show unique features caused by their movement. For example, the spiral galaxy D100 has long tails. These tails are created by a process called ram-pressure stripping. This happens as the galaxy moves through the cluster environment. Some galaxies in the cluster are also identified as ultra diffuse galaxies. These are much spread out compared to normal galaxies. The full extent of the cluster was not understood until the 1950s. Astronomers at the Mount Palomar Observatory conducted those important studies.

History shows that humans have studied this cluster for a long time. William Herschel visually noted the cluster in 1785. Later, Max Wolf performed a photographic survey in 1901. These early observations helped build our knowledge of the cluster. The cluster is one of the first galaxy clusters mentioned in astronomy literature. It remains a primary subject for modern astronomical research.

In 1933, a scientist named Fritz Zwicky discovered something amazing about the cluster. He noticed that the galaxies were moving extremely fast. They showed an average Doppler effect of 1000 km/s or more. Zwicky realized the visible matter could not hold them together. The galaxies were moving too fast to stay in a group. He proposed that a hidden mass must be present. He called this "dunkle Materie," which we now call dark matter.

Zwicky's math showed how much mass was actually missing. He calculated that the density needed to hold the cluster together was very high. It had to be at least 400 times greater than what visible matter suggested. Today, scientists believe that dark matter makes up about 90% of the cluster's mass. This discovery changed how we understand the entire universe. It proved that most of the matter in space is invisible.

We can also detect energy from the cluster using X-rays. An extended X-ray source was reported before August 1966. This was found using a balloon. A sounding rocket flight in 1964 did not detect it. Later, the Uhuru satellite observed a strong X-ray source near the center. Scientists suggested naming this source Coma X-1. This source is about 45 arc-minutes in size. Because it is so large, it is likely not just one single galaxy. The luminosity of this central source is 2.6 x 10^44 ergs/s.