Wen-Jun Tan

Gamma-ray burst 230307A lit up the sky like a thunderclap: in seconds, it released more energy than the Sun will emit over billions of years. Three detectors—GECAM-B, GECAM-C, and Fermi/GBM—were looking in the right direction at that moment.

In October 2022, the space-based detector GECAM-C caught the most powerful gamma-ray burst ever seen, GRB 221009A — an explosion that briefly became the brightest source of gamma rays in the sky. But the most interesting part came after: the instrument detected a series of additional flares, and one of them was record-breaking.

The Einstein Probe space telescope detected a celestial storm: after a short (0.4-second) gamma-ray burst — a cosmic lightning bolt — came a long roll of X-ray thunder. It lasted nearly 10 minutes. This is the first direct proof that such explosions leave a lingering X-ray afterglow.

A flashlight doesn't cast a uniform circle of light; it has a bright spot in the center and a blurred halo at the edges. If you switch it off quickly, the edges are the last to fade, and by how the light dies, you can guess the shape of the reflector.

An avalanche in a sandpile starts with a single grain. No one knows exactly where it will slip or how big the slide will be. But if you keep pouring sand, the pile itself reaches a state where avalanches of all sizes, from tiny trickles to massive collapses, follow the same law.