Y. Hayashi

A bus schedule drifts: if you don't check it, you'll miss your ride. Planets around other stars have the same problem – their crossings of the star's disk gradually shift. The ExoClock project pooled 30,000 observations from Earth and space to refine the schedule for 620 distant worlds. For 45% of the planets, transits were found to be off by hours.

Every second, invisible particles from space, cosmic rays, strike Earth's atmosphere. Colliding with air molecules, they produce showers of secondary particles, among which muons are especially abundant. A muon is a heavy cousin of the electron that lives only a couple of microseconds but still manages to reach the ground.

When a star like the Sun ages, it swells and sheds its outer layers. What remains is a small, dense white dwarf — the former core. Around it, planetary debris can remain: rocks, dust, even whole asteroids. They orbit like a carousel that's been taken apart, but the pieces are still spinning. Astronomers watched the white dwarf WD 1054-226 for six years.

During a thunderstorm, the sky acts like a giant battery: charge builds up in the cloud, and a lightning bolt discharges it. That charge is invisible, but cosmic particles (muons, which constantly rain down on Earth from space) can sense it. As a muon flies through a charged cloud, it speeds up or slows down slightly, and these changes reveal the voltage inside the cloud.