Father Maximilian Hell had received an offer he couldn’t refuse. King Christian VII of Denmark and Norway had invited him to lead an expedition to observe a transit of Venus across the Sun in 1769. Hell had already declined a couple of other offers. But this one was too good to pass up. So he began preparing for one of his top accomplishments – and biggest controversies.

Hell was born 300 years ago today, in modern-day Hungary. His father was chief engineer for the local mines, so science and math were a constant part of his upbringing. After he joined the Jesuit order, the queen of Austria and Hungary appointed him astronomer royal. He built a new observatory, in Vienna, and directed it for most of the rest of his life.

His transit expedition took him to a small island off the coast of Norway. He took three telescopes, two clocks, and a raft of other instruments. The goal was to measure the timing of Venus’s passage across the Sun. By combining observations from different locations on Earth, astronomers hoped to calculate the exact distance to the Sun.

Hell made good observations of the transit. But he didn’t report them to other scientists for many months. That raised suspicions that he’d changed them to match those of others.

The controversy continued until the late 1800s, when a top astronomer found that Hell’s reports were genuine – confirming Father Hell’s status as one of the leading astronomers of the 18th century.

Script by Damond Benningfield