Webb maps the universe’s dark matter across 800,000 galaxies

Using the James Webb Space Telescope, astronomers built a detailed map of dark matter by analyzing subtle light distortions (weak gravitational lensing) from roughly 800,000 background galaxies in the COSMOS field. The 255-hour NIRCam observations, with MIRI distance measurements and prior Hubble data, yield the most galaxy-dense dark‑matter map to date—about ten times more galaxies than ground-based surveys and twice as many as the Hubble map—providing new insights into how dark matter shapes galaxy growth and the cosmic web.