He emigrated to Russia in 1768. He studied the motions of comets. He computed the orbit of comet D/1770 L1 (Lexell), and it is named after him although it was discovered by Charles Messier. This comet made the closest known approach to Earth by any comet in history (although asteroids have come closer), making it the first known near-Earth object; the exact distance is not known but has been estimated to have been within 3 million km. The comet was later ejected from the solar system by a close encounter with Jupiter.
He was also the first to compute the orbit of Uranus soon after its discovery and realized from its orbit that it was a planet rather than a comet. He also found that Uranus was being perturbed and deduced the existence of another planet (the eventual Neptune), although the position of Neptune was not calculated until much later by Urbain Le Verrier.
AndersJohanLexell (December 24 1740 – December 11 1784 (Julian calendar: November 30)) was a Finnish-Swedish-born Russian astronomer and mathematician.
Lexell showed that the comet had had a much larger perihelion distance until an encounter Jupiter in 1767, and he predicted that, after encountering Jupiter again at an even closer distance two revolutions later, in 1779, it would be altogether expelled from the inner solar system.
AndersJohanLexell at the MacTutor History of Mathematics archive.
He computed the orbit of comet D/1770 L1 (Lexell), and it is named after him although it was discovered by Charles Messier.
Lexell showed that the comet had had a much larger perihelion distance until an encounter Jupiter in 1767, and he predicted that, after encountering Jupiter again at an even closer distance two revolutions later, in 1779, it would be altogether expelled from the inner solar system.
This is understandable that cash makes people independent. But how to act if one has no cash? The one way only is to receive the loans or college loan.
HOBBSDEBRA18 26th March 2010
That's not very easy to deal with several actions at the same time, especially when you need to accomplish the analytical essay. The only essay writers service would cope even with the most complicated tasks.
ODRYBG18 29th January 2010
University studying process requires creative writing skills, nevertheless, students, which are short of time can destroy their success. Thus, to order the essay topic from the essay writers service could be a good solution.
There are 2 more (non-authoritative) comments on this page
Feeds |
Contact