Henri Becquerel

Imagine finding a new kind of invisible light that can fog a photograph by itself!

Henri Becquerel was a French scientist in the late 1800s who accidentally discovered something huge: radioactivity. In 1896 he noticed uranium salts could blacken photographic plates even without sunlight.

His experiment was simple: uranium-covered plates were kept in a drawer wrapped in black paper. Even on cloudy days the plates were fogged. He realized the uranium itself sent out tiny invisible rays all the time.

This discovery opened a new field—nuclear physics. It helped other scientists like Marie and Pierre Curie find more radioactive stuff. Becquerel shared the 1903 Nobel Prize in Physics with the Curies.

Today we measure radioactivity in becquerels, named after him. Radioactivity led to ways to image the body, to treat some cancers, and to powerful technologies like nuclear energy.

Becquerel showed that careful curiosity — and a lucky accident — can reveal hidden parts of nature. His discovery changed science forever.