Although dark matter is invisible, astronomers can still work out where it is in space from the effect that its gravity has on the things around it – like seeing a sofa cushion being pushed down by an invisible man. By looking at the distorted shapes of these galaxies, a team of astronomers has worked out how the invisible material is spread out in the galaxy cluster. Surprisingly, they found that the dark matter isn’t spread out like a football, as they had expected, but that it is shaped more like a rugby ball.
Credit:
X-ray: NASA/CXC/Caltech/A.Newman et al/Tel Aviv/A.Morandi & M.Limousin; Optical: NASA/STScI, ESO/VLT, SDSS