Cosmic Collision Frees Normal Matter from Dark Matter

Astronomers who used NASA's Chandra X-ray Observatory will host a media teleconference at 1 p.m. EDT Monday, Aug. 21, to announce how dark and normal matter have been forced apart in an extraordinarily energetic collision. Audio of the event will be streamed live on the Web at:


  • Dr. Maxim Markevitch, Astrophysicist, Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass.

  • Dr. Douglas Clowe, Postdoctoral fellow, University of Arizona, Tucson, Ariz.

  • Dr. Sean Carroll, Assistant Professor in the Physics Department and Enrico Fermi Institute at the University of Chicago


  1. Hubble/Magellan Optical Image

  2. Chandra X-ray Image, Labeled

  3. X-ray/Optical Composite

  4. Animation of Cluster Collision MPEG | Quicktime

  5. Gravitational Lensing Explanation

  6. X-ray/Optical/Lensing Map Composite

Supplementary Graphics:

  1. Chandra/Lensing Map Composite

  2. Close-up of Galaxy from Full Field

  3. Motion Graphic

  4. Chandra X-ray Image

  5. Motion Graphic


  • Paper title: A Direct Empirical Proof of the Existence of Dark Matter (pdf format)
    • Full Author List: Douglas Clowe (Steward, Univ. of Arizona), Marusa Bradac (KIPAC, Stanford), Anthony Gonzalez (Univ. of Florida), Maxim Markevitch (Harvard-Smithsonian CfA), Scott Randall (Harvard-Smithsonian CfA), Christine Jones (Harvard-Smithsonian CfA), Dennis Zaritsky (Steward, Univ. of Arizona)
    • After 8pm Eastern on Monday, August 21, Clowe et al. paper will appear at: and a related paper by Bradac et al will appear at:
  • Telescopes used: NASA's Chandra X-ray Observatory, NASA's Hubble Space Telescope, 6.5m Magellan telescope, 2.2m ESO Wide Field Imager
  • Distance to 1E 0657-56: 3.4 billion light years
  • Cluster Collision Speed: 10 million mph


Instant Replay Plus Information:
An instant replay of the media telecon will be available after the end of the telecon. Call: 800-819-5739 (toll free). This service will be available until AUG-28-06 10:59 PM (CT).

NASA-TV Video File:
A video file about the discovery will air on NASA-TV at noon, Aug. 21. NASA-TV is carried on an MPEG-2 digital signal accessed via satellite AMC-6, at 72 degrees west longitude, transponder 17C, 4040 MHz, vertical polarization. It's available in Alaska and Hawaii on AMC-7 at 137 degrees west longitude, transponder 18C, at 4060 MHz, horizontal polarization.