51.0 MB (1.8 MB compressed)
3626 x 4919 pixels
30.7 x 41.7 cm ⏐ 12.1 x 16.4 in (300dpi)
SCIENCE PHOTO LIBRARY SCIENCE PHOTO LIBRARY
Friedrich Bessel. Portrait of Friedrich Wilhelm Bessel (1784-1846), German astronomer. He studied the perturbations of planetary and stellar motions, inventing the Bessel mathematical func- tions to aid his analyses. In 1838 he was the first to establish the distance to a star by measuring its apparent angular motion (parallax), using 61 Cygni as his first object. He predicted that a small companion star formed a binary system with Sirius. He computed the mass of Jupiter by analysing the orbits of its satellites, and found that it had a relatively low density. He suggested the existence of the planet beyond Uranus, but died a few months before the discovery of Neptune.
Model release not available. Property release not required.