Complex sentence: John Glenn became the first American to reach orbit on 20 February 1962, he was the third person to do so, after soviet Gherman Titov had made a day long flight in August 1961.
Split into simpler sentences: John Glenn became the first American to reach orbit on 20 February 1962. He was the third person to do so, after Soviet Gherman Titov made a day-long flight in August 1961.