ESA Science & Technology03-Aug-2005 11:16:05

Galaxies and the Expanding Universe

Distant Galactic Clusters

Beyond our local group of galaxies further clusters and superclusters of galaxies are known to exist.

The nearest galactic cluster is the Virgo Cluster containing around 2000 objects at a distance of around 50 million years ± 10%.  Virgo€™s gravity is so strong, thanks to its enormous mass, that our Local Group of galaxies is affected by its pull. Called the Virgo-Centric flow, this immense force will eventually pull nearby galaxies close enough to join the Virgo cluster.

The Coma Cluster is more than 350 million light years away from Earth in the constellation of Coma Berenices. The Coma cluster, thought to contain over 1000 galaxies, is nearly spherical in shape. Its galaxies, estimated at around 15 billion years old, are mainly elliptical.

A galactic supercluster is formed when lots of clusters are drawn together by gravity. They are the largest structures in the Universe, and can contain tens of thousands of galaxies that span hundreds of millions of light years.

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