Dark matter map. Computer model of dark matter (red) distribution in the universe, the first time the invisible dark matter between visible objects has been mapped. Its position has been inferred from the effect its gravitational pull has on the light from more distant galaxies (blue), which are seen to be slightly elongated parallel to the dark matter filaments. The mass of the observable universe is only around a tenth of that calculated from observations, with dark matter thought to constitute the missing mass. This work was done by Yannick Mellier and his team from the Paris Astro- physics Institute, France, using the Canada- France-Hawaii Telescope on Mauna Kea, Hawaii, USA.