The James Webb Space Telescope has only been watching the sky for a few weeks, and it has already delivered a startling finding: tens, hundreds, maybe even 1000 times more bright galaxies in the early universe than astronomers anticipated.
“No one was expecting anything like this,” says Michael Boylan-Kolchin of the University of Texas, Austin. “Galaxies are exploding out of the woodwork,” says Rachel Somerville of the Flatiron Institute.
Galaxy formation models may now need a revision, as current ones hold that gas clouds should be far slower to coalesce into stars and galaxies than is suggested by Webb’s galaxy-rich images of the early universe, less than 500 million years after the big bang. “This is way outside the box of what models were predicting,” says Garth Illingworth of the University of California (UC), Santa Cruz.
Webb, a NASA-led orbiting observatory with contributions from the European and Canadian space agencies, began observing in late June from its vantage point 1.5 million kilometers from Earth. Much of its time so far has been devoted to projects meant to show off its capabilities, such as the Cosmic Evolution Early Release Science (CEERS) Survey. Webb is designed to delve deeper into cosmic history than its predecessor, the Hubble Space Telescope. Its 6.5-meter mirror—with six times the area of Hubble’s—can catch more light from distant sources, and unlike Hubble it operates at infrared wavelengths, making Webb more sensitive to those faraway sources, whose light is stretched to longer, redder wavelengths by cosmic expansion. [Continue reading…]