WASHINGTON—The detection of a highly compact galaxy that formed relatively soon after the Big Bang and displayed an impressive rate of star formation is the latest example of how the James Webb Space Telescope is reshaping our understanding of the early universe.
Scientists said the galaxy, dating to 13.3 billion years ago, has a diameter of approximately 100 light-years—about 1,000 times smaller than the Milky Way—but forms new stars at a rate very similar to that of our much-larger present-day galaxy. A light-year is the distance light travels in a year, 5.9 trillion miles (9.5 trillion km).
It existed about 510 million years after the Big Bang event marking the universe’s origin. The universe at the time was less than 4 percent of its current age….