When he was just 14 years old, Franz von Paula Gruithuisen found himself in the middle of the Austro-Turkish War. He wasn’t a prisoner or a refugee. Instead, he was a field surgeon. But just a year later, he was using a small telescope to observe the Moon. Those episodes marked the beginning of a diverse career in science. It featured both important contributions and false starts.

Gruithuisen was born 250 years ago tomorrow, in a castle in Bavaria. His father was a servant, so his early education was limited. But the youngster was so bright that he quickly earned new opportunities. He taught medical students topics from A to Z — anthropology to zoology. And he devised new medical procedures and instruments. But in 1826, he became a professor of astronomy.

He was especially interested in the Moon, which he thought was inhabited. He even saw what appeared to be a city, which he named Wallwerk.

His main contribution to lunar science, though, was his idea about lunar craters. He was the first astronomer to suggest they were carved by collisions with space rocks. His idea didn’t gain a lot of early support. In fact, it was disputed until the 1960s. Today, though, there’s no doubt about it — the Moon’s craters are the result of giant impacts.

You can see some of the craters tonight. The Moon is high in the sky at sunset, and stays in view most of the night. It’s near the twin stars of Gemini.

Script by Damond Benningfield