Pierre Gassendi, French mathematician, astronomer, and philosopher (died 1655)

Pierre Gassendi was a French philosopher, Catholic priest, astronomer, and mathematician. While he held a church position in south-east France, he also spent much time in Paris, where he was a leader of a group of free-thinking intellectuals. He was also an active observational scientist, publishing the first data on the transit of Mercury in 1631. The lunar crater Gassendi is named after him.

January 22 is the 22nd day of the year in the Gregorian calendar; 343 days remain until the end of the year.