Yuichi Harikane

A massive galaxy cluster acts as a giant lens. Its gravity warps the fabric of space, and the light of distant objects, bending around this curvature, is amplified and split into multiple images.

Thanks to gravitational lens — an effect predicted by Fritz Zwicky, where a galaxy cluster acts like a magnifying glass — the James Webb Space Telescope spotted two red dots in a galaxy 800 million years after the Big Bang.

The galaxy CEERS2-588 flared up like a bonfire fed with an armful of wood all at once. Just 400 million years after the Big Bang, it had already built up a mass of a billion suns and ignited countless stars. But then the fuel ran out, and over the last 10 million years, star formation in it has almost completely ceased.

When the James Webb Space Telescope turned its gaze deep into time, astronomers expected to see familiar galaxies. Instead, the images were dotted with a scattering of bright, incredibly compact red dots.

For thirteen billion years, light battled through cosmic emptiness. It bent around massive galaxy clusters that, as Einstein predicted, acted as giant lenses — amplifying and distorting the distant glow. In 2023, the NIRSpec instrument on the James Webb Space Telescope captured this light and spread it into spectra.

Forty reddish sparks frozen in the images from JWST. The telescope spotted them in the depths of space, at distances where the Universe was less than two billion years old. These objects are active galactic nuclei — very compact and unusually red. Their color earned them the nickname 'little red dots' (LRDs).

The night sky is full of deceptive lights. Astronomers were searching for galaxies that ignited in the first few hundred million years after the Big Bang: their light has traveled to us for nearly 13 billion years. Six faint smudges were selected from images taken by the Hubble and Spitzer space telescopes.