Aaron J. Romanowsky

The James Webb Space Telescope spotted a luminous streak in a distant galaxy, like the wake of a speedboat, only two hundred thousand light-years long. At the head of this trail races a supermassive black hole, plowing through tenuous gas at 954 km/s. The gas gets compressed, heats up, and glows.

A river of stars (not a cluster, but a distinctly elongated, glowing ribbon) crosses the outskirts of a distant galaxy. Such a stream was spotted in data from the first survey by the Vera Rubin Observatory. It stretches along the minor axis of the galaxy LEDA 751050, like a scarf streaming from the galactic disk. The stream is enormous: 130 by 15 kiloparsecs.

Galaxies without dark matter are like beads from which the invisible thread has been ripped. Stretching around the elliptical NGC 1052 is a chain of eight ghostly dim dwarfs: they contain almost none of the mysterious mass that makes spiral arms rotate. Vera Rubin first showed that without the invisible framework, stars would fly apart.

Faint galaxies scattered across the Perseus cluster are like ghosts among their bright neighbors. They are so diffuse that distant objects shine through them, and they contain hundreds of times fewer stars than our Milky Way.