Joseph von Fraunhofer

Joseph von Fraunhofer rose from orphaned poverty to become the father of astrophysics. Apprenticed to a glassmaker as a boy, he survived the collapse of his master's workshop and used a gift from the Prince Elector of Bavaria to educate himself in optics. Fraunhofer revolutionized telescope optics by developing methods to produce the finest glass lenses in the world. But his most far-reaching contribution was his systematic study of the dark lines in the solar spectrum. While these lines had been noticed by William Hyde Wollaston in 1802, Fraunhofer mapped and cataloged 574 of them with unprecedented precision. The most prominent are still called Fraunhofer lines. He did not live to learn what caused them — that would come decades later when Kirchhoff and Bunsen showed they were absorption signatures of chemical elements. But Fraunhofer's meticulous work laid the foundation for spectroscopy, the tool that would eventually reveal the composition, temperature, and motion of stars.

• Mapped 574 dark absorption lines in the solar spectrum (Fraunhofer lines) • Built the finest refracting telescopes and lenses of his era • Invented the diffraction grating for precise spectral analysis • Laid the foundation for stellar spectroscopy and astrophysics