Complex sentence: Theodor Johan Christian Ambders Brorsen (July 29 1819--May 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--May 31 1895) was a Danish astronomer. He discovered a number of comets, including the lost periodic comet 5D/Brorsen and the periodic comet 23P/Brorsen-Metcalf.