Complex sentence: Joseph Ritter von Fraunhofer (6 March 1787--7 June 1826) was a German physicist, known for discovering the dark absorption lines known as Fraunhofer lines in the Sun's spectrum, and for making excellent optical glass and achromatic telescope objectives.
Split into simpler sentences: Joseph Ritter von Fraunhofer (6 March 1787--7 June 1826) was a German physicist. He is known for discovering the dark absorption lines known as Fraunhofer lines in the Sun's spectrum, and for making excellent optical glass and achromatic telescope objectives.