The Virgo Cluster: Hot Plasma and Dark Matter
19.04.1996

This ROSAT image of the Virgo cluster of galaxies reveals a hot X-ray emitting plasma or gas with a temperature of 10-100 million degrees pervading the cluster. False colors have been used to represent the intensity of X-ray emission.

Abell 2744: Pandoras Cluster of Galaxies
29.06.2011

Why is this cluster of galaxies so jumbled? Far from a smooth distribution, Abell 2744 not only has knots of galaxies, but the X-ray emitting hot gas (colored red) in the cluster appears distributed differently than the dark matter.

NGC 1316: After Galaxies Collide
4.04.2005

How did this strange-looking galaxy form? Astronomers turn detectives when trying to figure out the cause of unusual jumbles of stars, gas, and dust like NGC 1316. A preliminary inspection indicates that NGC 1316 is an enormous elliptical galaxy that includes dark dust lanes usually found in a spiral.

APOD: 2009 April 7 The Colliding Spiral Galaxies of Arp 274
7.04.2009

Two galaxies are squaring off in Virgo and here are the latest pictures. When two galaxies collide, the stars that compose them usually do not. This is because galaxies are mostly empty space and, however bright, stars only take up only a small fraction of that space.

Cosmic Collisions in a Galaxy Cluster
22.07.1999

Hundreds of galaxies appear as faint smudges of light in this Hubble Space Telescope picture of galaxy cluster MS1054-03. Eight billion light-years away, the cluster is among the most distant known clusters of galaxies and is now reported to contain the largest number of colliding galaxies ever found in a cluster.

Dark Matter Map
14.08.2003

The total mass within giant galaxy cluster CL0025+1654, about 4.5 billion light-years away, produces a cosmic gravitational lens -- bending light as predicted by Einstein's theory of gravity and forming detectable images of even more distant background galaxies.

The Colliding Spiral Galaxies of Arp 271
21.07.2008

What will become of these galaxies? Spiral galaxies NGC 5426 and NGC 5427 are passing dangerously close to each other, but each is likely to survive this collision. Most frequently when galaxies collide, a large galaxy eats a much smaller galaxy.

Blue Stragglers In NGC 6397
22.06.2000

In our neck of the Galaxy stars are too far apart to be in danger of colliding, but in the dense cores of globular star clusters star collisions may be relatively common. In fact...

Cartwheel Of Fortune
19.12.1998

By chance, a collision of two galaxies has created a surprisingly recognizable shape on a cosmic scale - "The Cartwheel Galaxy". The Cartwheel is part of a group of galaxies about 500 million light years away in the constellation Sculptor (two smaller galaxies in the group are visible on the right).

Dark Matter, X rays, and NGC 720
26.10.2002

Elliptical galaxy NGC 720 is enveloped in a cosmic cloud of x-ray emitting gas. Seen in this false color image from the Chandra X-ray Observatory, the extreme temperature of the gas - about 7 million...