What are the mysterious ‘little red dots’ in images of space?

When the James Webb Space Telescope first began sending back images in 2022, astronomers noticed something they had never seen before: little red dots speckled across the sky. They didn't look like any known celestial objects. As Dr. Rohan Naidu, an astrophysicist at the University of Hawaii, put it, "every astronomer is secretly hoping to find the unknown unknowns … things that were never predicted or theorized that just jump out of you." The little red dots were exactly that. They were everywhere, and they didn't match anything in the existing astronomical databases. Since then, roughly a thousand papers have been written about them, and a new one seems to appear every day. The field is scrambling to figure out what these objects are.

What the little red dots are not

The little red dots appear in nearly every deep image from JWST. Naidu estimates that at least one percent of all galaxies in the early universe may host one. They are an "early universe special"—they appear only in the first billion years after the Big Bang and become vanishingly rare by the time the universe reaches the age of the Milky Way. That is why they were never seen before: no previous telescope was powerful enough to peer that far back in time, and none could see the infrared light in which these objects shine brightest.