Annelies Mortier

The young star TOI-451 wobbles slightly as three planets circle it. Each wobble is like the tremor of a spiderweb when a tiny spider crawls across it. Astronomers caught this tremor to learn how heavy the planets are. They watched the star for several months using telescopes on Earth. The planets kept passing in front of the star, briefly dimming its light.

For six straight years, the HARPS-N telescope on La Palma island stared at the Sun as if it were a distant star — taking spectra, tracking brightness, and recording every quiver of spectral lines. All this was to understand how to distinguish a star's subtle sway from a genuine planetary signal. A star doesn't sit still: its surface boils like a pot of soup.