Complex sentence: Theodor Johan Christian Ambders Brorsen (July 29,1819--March 31,1895) was a Danish astronomer best known for his discovery of five comets, including the lost periodic comet 5D/Brorsen and the periodic comet 23P/Brorsen-Metcalf.
Split into simpler sentences: Theodor Johan Christian Ambders Brorsen (July 29,1819--March 31,1895) was a Danish astronomer. He is best known for his discovery of five comets, including the lost periodic comet, 5D/Brorsen, and the periodic comet 23P/Brorsen-Metcalf.