By Will DunhamWASHINGTON, Jan 26 (Reuters) – Using observations from the James Webb Space Telescope in a patch of the sky covering almost three times the area of the full moon, scientists have created the most detailed cosmic map to date of the mysterious substance called dark matter that accounts for most of the stuff that populates the universe.Ordinary matter makes up stars, planets, people and everything else we can see. But it represents only about 15% of all the matter in the cosmos. The rest is dark matter, which does not emit or reflect light, making it invisible to the human eye and to telescopes.AdvertisementAdvertisementAdvertisementAdvertisementScientists infer its existence based on the gravitational effects it exerts on a large scale such as how quickly galaxies rotate, how galaxy clusters are held together and how light from distant objects bends as it passes through massive cosmic structures.The new map of the distribution of dark matter was based on this phenomenon of light bending – causing subtle distortions in the shape of roughly 250,000 distant galaxies as observed by Webb – thanks to the gravitational effects of matter along the line of sight.A previous map of dark matter was based on observations by the Hubble Space Telescope. The new map, powered by Webb’s greater capabilities, offers double the resolution of the previous map, spans more parts of the cosmos and peers further back in time – effectively looking to roughly 8 to 10 billion years ago, a key period for galaxy formation.”This allows us to resolve finer dark matter structures, detect mass concentrations that were previously unseen, and extend dark-matter mapping in …
