Danilo Marchesini

The 'Sleepy' galaxy in the early universe furiously gave birth to stars, but after 300 million years it fell asleep. A record-breaking hydrogen dip in its glow showed that not all bright early galaxies become giants—some doze off and turn into dwarfs.

Using NIRCam on JWST, astronomers studied four supermassive quiescent galaxies whose light has been traveling to us for over 11 billion years. It turns out that in three of them, the color shifts smoothly from center to outskirts: red old cores surrounded by bluer, younger regions. This color map re