The James Webb Space Telescope, a Window Into the Past

After two and a half decades of planning and construction, the James Webb Space Telescope (JWST)—the largest and most advanced space telescope in history—was launched from French Guiana on Christmas Day last year. It spent the winter and spring in its “commissioning” phase, a science-y way of saying it was being calibrated as it zoomed through space a million miles from Earth. Originally, NASA was shooting for the telescope to be completed as early as 2007 with a price tag as low as $1 billion, but it turned out to be more complex to build than anticipated, and it ended up costing almost $10 billion.

The images the JWST sent back this summer weren’t only breathtaking, even when compared with JWST’s predecessor, Hubble; they also offered preliminary answers to heavy questions. John Mather, a Nobel Prize-winning cosmologist at NASA, asked some during a livestream of the photo reveal: “What happened after the Big Bang? How did the galaxies grow? How did the first black holes grow? What happened all the way from there to here?” The JWST, he said, “is our time machine.” Because the light from distant objects takes so long to reach the telescope, we’re seeing some of them as they were when the universe, thought to be 13.8 billion years old, was younger than 1 billion.