The work of Rubin and her team helped to firmly establish the notion of dark matter. They also discovered single galaxies, not just clusters, have more mass than their observable light suggested. astronomer Vera Rubin and her colleagues confirmed this result by studying galaxy rotation. The speed he measured implied the cluster had much more mass than the observable light suggested. Clusters are like merry-go-rounds: Their speed of revolution depends on the weight and position of the objects in the clusters, like the weight of the objects and their positions on a merry-go-round. He studied the so-called Coma galaxy cluster and, specifically, how fast it revolves. The Swiss astronomer Fritz Zwicky first used the term 'dark matter' in the 1930s. The invisible matter that we can't detect is called 'dark matter.' By doing this, they discovered that there must be five times more material in the clusters than we can detect.

Scientists look at that gas and measure how much there is between galaxies in clusters. The gas only can be seen as X-rays or gamma rays. In some clusters, the space between galaxies is filled with gas so hot, scientists cannot see it using visible light telescopes. Something must hold our solar system, galaxies and clusters of galaxies together. Clumps of matter in smashed into each other, and the planets in our solar system began to form around the sun. Those clusters are made up of the galaxies and all the material between the galaxies.

The universe was featureless.Īs time passed, the first stars formed. Image credit: Hubble Telescope/NASA For the first 150 million years after the Big Bang, there were no galaxies or stars or planets. Five starlike images appear when light from a single quasar passes through a gravitational lens.

What is matter made of