Dennis Bodewits

Comet 3I/ATLAS was spotted when it entered the Solar System from interstellar space. The James Webb Telescope split the light from its gas cloud into a rainbow, a spectrum, and in this pattern, the lines of rare molecules with deuterium (heavy hydrogen) appeared.

When the interstellar comet 3I/ATLAS approached the Sun, its tail lit up with a metallic sheen, as if a tin can full of nickel and iron had burst open. By breaking down its light into colors, astronomers detected the lines of these metals using spectral analysis.

In the summer of 2021, comet 7P/Pons-Winnecke put on quite a show. A network of telescopes, the Las Cumbres Observatory, tracked it for nearly three months and counted eight sudden outbursts.