Complex sentence: John Herschel Glenn, Jr. (born July 18,1921) is a former United States Marine Corps pilot, astronaut, and United States senator who was the first American to orbit the Earth and the third American in space.
Split into simpler sentences: John Herschel Glenn, Jr. (born July 18,1921) is a former United States Marine Corps pilot, astronaut, and United States senator. He was the first American to orbit the Earth and the third American in space.