Radiation belts are regions where energetic charged particles become trapped by a planet’s magnetic field. Earth has two permanent radiation belts that can interfere with satellites and pose risks to astronauts. When the planet is closer to the sun, radiation belts appear only about 20% of the time. Although scientists still do not know exactly how powerful Mercury’s radiation belts are, they now know these regions exist and appear under predictable conditions. The upcoming BepiColombo mission will provide the first direct measurements of Mercury’s radiation belts.