James McCormac

Astronomers have discovered a close pair of stars whose orbital dance is speeding up year after year. These are white dwarfs — superdense, cooled remnants of stars, roughly the size of Earth, where matter is compressed to a degenerate state.

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.

When a planet passes in front of its star, some starlight filters through its atmosphere. Gases in the atmosphere block certain colors and let others through, like the colored glass of a stained-glass window. By seeing which colors are dimmed, you can figure out what the air of a distant world is made of.

In deep space, 95 parsecs from Earth, nature is assembling a planetary clock. The model HD 114082 is a prototype, only 15 million years old. Two massive pendulums — exoplanets b and c — are already swinging with periods of 225 and 314 days, but the whole mechanism is still covered in the construction dust of a debris disk.