Abell 1689 galaxy cluster. Combined Hubble Space Telescope (HST) and Chandra X-ray Observatory (CXO) image of the massive galaxy cluster Abell 1689. The purple haze is X-rays from hot gas between the galaxies, indicating that they may be in the process of merging. The galaxies (yellow) were observed by the HST. The long arcs are caused by gravitational lensing of background galaxies by matter in the galaxy cluster.Abell 1689 is located in the constellation of Virgo and is around 2.2 billion light years from Earth. The area seen here is hundreds of thousands of light years across. This image was obtained from 2004 to 2006, using the CXO's Advanced CCD Imaging Spectrometer (ACIS).