Michael Cretignier

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.

Scientists search for planets around distant stars by detecting a slight wobble in the star's motion: the planet tugs on the star, making its light shift slightly toward the blue and then toward the red. But stars have their own ripples — dark spots and bright faculae on their surfaces. These also shift the light, making it hard to tell them apart from a planet.