Heinrich Wilhelm Matthaus Olbers

Heinrich Wilhelm Matthäus Olbers , 1758-1840, German astronomer and physician. He originated (1797) the first satisfactory method for calculating the orbits of comets, but despite the fame it brought him, he remained an amateur astronomer and became a physician. However, he continued his research on comets and discovered several. He was the first to detect the comet of 1815 (Comet Olbers, period 72.7 years). He also discovered two asteroids, Pallas (1802) and Vesta (1807). Considering their orbits and those of the other asteroids then known, Olbers concluded that they are fragments of a disrupted planet that had formerly revolved around the sun. He is best remembered for Olbers' paradox: "Why is the sky dark at night?" Assuming that space is infinite and filled with stars, he suggested, the entire sky should be as bright as the surface of the sun. The question had originally been raised by Kepler. Others offered one of several incorrect resolutions to the paradox, suggesting that absorbing clouds obscured our view of the distant stars. The correct explanation is that our universe is finite both in time and place, and the total amount of matter and energy is far too small to light up the night sky.

Olbers, HeinrichWilhelmMatthäus (1758–1840)Germanphysician and amateur astronomer. The method he developed to calculate the orbit of a comet he discovered in 1796 (now designated C/1796 F1) became standard in the 19th century. He later suggested that comets' tails are somehow expelled from their heads by the Sun, thereby anticipating the discovery of radiation pressure. In 1802, a year to the day after its discovery, Olbers recovered the asteroid Ceres in the position predicted by C. F.Gauss. Olbers subsequently discovered Pallas (1802) and Vesta (1807). In 1823 he first pointed out what has come to be called Olbers' paradox.