| Friedrich Bessel | 1784-1846 Prussian |
first to measure distance to the star 61 Cygni; proposed that Sirius has an unseen companion; worked out the mathematical analysis of what are now known as Bessel functions |
| Joseph von Fraunhofer | 1787-1826 German |
made detailed wavelength measurements of hundreds of lines in the solar spectrum; designed an achromatic objective lens |
| Johann Franz Encke | 1791-1865 German |
discovered the first short-period comet, now called Encke’s comet |
| Friedrich von Struve | 1793-1864 German-born Russian |
founded the study of double stars; published catalog of over 3000 binary stars; first to measure distance to the star Vega |
| Wilhelm Beer | 1797-1850 German |
prepared and published maps of the Moon and Mars |
| Thomas Henderson | 1798-1844 Scottish |
first to measure distance to a star (Alpha Centauri) |
| William Lassell | 1799-1880 British |
discovered Triton, the largest satellite of Neptune |
| Sir George Airy | 1801-1892 British |
improved orbital theory of Venus and the Moon; studied interference fringes in optics; made a mathematical study of the rainbow |
| Urbain Le Verrier | 1811-1877 French |
accurately predicted the position of Neptune, which led to its discovery |
| Johann Gottfried Galle | 1812-1910 German |
first person to observe Neptune, based on calculations by French mathematician, Urbain Le Verrier; however, Neptune’s discovery is usually credited to Le Verrier and English astronomer, John Crouch Adams, who first predicted its position |
| Anders Ångström | 1814-1874 Swedish |
discovered hydrogen in the solar spectrum; source of the Angstrom unit |
| Daniel Kirkwood | 1814-1895 American |
discovered the “Kirkwood gaps” in the orbits of the asteroids between Mars and Jupiter; explained the gaps in Saturn’s rings |
| William Huggins | 1824-1910 British |
first to show that some nebulae, including the great nebula in Orion, have pure emission spectra and thus must be gaseous |
| Sir Joseph Lockyer | 1836-1920 British |
discovered in the solar spectrum a previously unknown element that he named helium |
| Henry Draper | 1837-1882 American |
made first photograph of a stellar spectrum (that of Vega); later photographed spectra of over a hundred stars and published them in a catalog; studied spectrum of Orion Nebula, which he showed was a dust cloud |
| Edward Charles Pickering | 1846-1919 American |
discovered the first spectroscopic binary star, Mizar |
| Jacobus Cornelius Kapteyn | 1851-1922 Dutch |
discovered that the proper motions of stars were not random, but stars could be divided into two streams moving in opposite directions, representing the rotation of our galaxy |
| Edward Barnard | 1857-1923 American |
discovered eight comets and Almathea, the fifth moon of Jupiter; also discovered star with largest proper motion, now called Barnard’s star |