Christoph Mordasini

Astronomers caught the young planet AU Mic b in the act of hiding behind its star. The Spitzer telescope tracked its infrared glow: as the planet slipped behind, the system's total light dimmed slightly. The dip was just 171 parts per million, like a single drop of ink in ten buckets of water.

Seven hours: that's how long a year lasts on TOI-4552b. It whips around its star faster than some moons orbit Earth. The star is a dim red dwarf, four times smaller than the Sun, but the planet is so close that it receives hundreds of times more heat than we do.