In observations spied through one of the most powerful telescopes in the world, the 33-foot (10-meter) Keck I Telescope in Hawaii, astronomers led by Sebastiano Cantalupo of the University of California, Santa Cruz, now report that they have detected a very large, luminous filament of gas extending about 2 million light-years across intergalactic space, exactly as predicted by theory. Image copyright S. Cantalupo (UCSC) Image caption The observed portion of the cosmic web (cyan) is about 2 million light-years across 
 
 The cosmic web suggested by the standard model is mainly made up of mysterious "dark matter". The cosmic filament found in the current study is part of the cosmic web that keeps the galaxy, including our Milky Way together. Astronomers hope to understand both the structure of the universe and the development of galaxies such as our own Milky Way by unraveling the secrets of the cosmic web. The web is observed in the findings from computer simulations of the development of structure in the universe, which reveal the dispersion of dark matter on large scales, including the dark matter halos in which galaxies develop and the cosmic web of filaments that link them. "The light from the quasar is like a flashlight beam, and in this case we were lucky that the flashlight is pointing toward the nebula and making the gas glow. We think this is part of a filament that may be even more extended than this, but we only see the part of the filament that is illuminated by the beamed emission from the quasar.” 
 
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– Scientists have seen a tendril of dark matter for the first time, and all it took was a "cosmic flashlight." Using the Keck telescope in Hawaii, a scientific team spotted the dark matter in a gas cloud illuminated by the radiation of a distant quasar, the BBC reports. "The light from the quasar is like a flashlight beam," said Sebastiano Cantalupo, lead author of the report. Lit by that beam, the glowing hydrogen of the gas cloud traced out the dark matter lying behind it. This all supports a theory that galaxies are wrapped up in filaments of gas that stretch across space like a web, National Geographic reports. About 85% of the web is said to be dark matter, Nature World News explains, and galaxies sit like spiders on intersections of the web. Gravity is what keeps us, and all matter, sitting on these filaments, and now one has actually been observed. It's "giving us the first picture of extended gas between galaxies," co-author J. Xavier Prochaska tells The Space Reporter. "It provides a terrific insight into the overall structure of our universe."