Alexis Bouvard (June 27, 1767 - June 7, 1843) was a French astronomer, born in Contamines, France. June 27 is the 178th day of the year (179th in leap years) in the Gregorian Calendar, with 187 days remaining. ... 1767 was a common year starting on Thursday (see link for calendar). ... June 7 is the 158th day of the year in the Gregorian calendar (159th in leap years), with 207 days remaining. ... 1843 was a common year starting on Sunday (see link for calendar). ... An astronomer or astrophysicist is a scientist whose area of research is astronomy or astrophysics. ...

Bouvard's achievements included the discovery of eight comets and the compilation of astronomical tables of Jupiter, Saturn and Uranus. While the former two tables were eminently successful, the latter showed substantial discrepancies with subsequent observations. This led Bouvard to hypothesise the existence of an eighth planet responsible for the irregularities in Uranus' orbit. The position of Neptune was subsequently calculated, independently, by John Couch Adams and Urbain Le Verrier after his death. Comet Hale-Bopp, showing a white dust tail and blue gas tail (February 1997) A comet is a small astronomical object similar to an asteroid but composed largely of ice. ... Atmospheric characteristics Atmospheric pressure 70 kPa Hydrogen ~86% Helium ~14% Methane 0. ... Atmospheric characteristics Atmospheric pressure 140 kPa Hydrogen >93% Helium >5% Methane 0. ... Atmospheric characteristics Atmospheric pressure 120 kPa Hydrogen 83% Helium 15% Methane 1. ... A hypothesis (= assumption in ancient Greek) is a proposed explanation for a phenomenon. ... A planet (from the Greek πλανήτης, planētēs which means wanderer or more forcefully vagrant, tramp) is a body of considerable mass that orbits a star and that produces no energy through nuclear fusion. ... Atmospheric characteristics Atmospheric pressure 120 kPa Hydrogen 83% Helium 15% Methane 1. ... In physics, an orbit is the path that an object makes, around another object, whilst under the influence of a source of centripetal force, such as gravity. ... Atmospheric characteristics Atmospheric pressure 100-300 kPa Hydrogen >84% Helium >12% Methane 2% Ammonia 0. ... For other people named John Adams, see John Adams (disambiguation). ... Urbain Le Verrier. ...

Bouvard was director of the Paris Observatory. He died in Paris. The Paris Observatory (in French, Observatoire de Paris or Observatoire de Paris-Meudon) is the foremost astronomical observatory of France, and one of the largest astronomical centers in the world. ... The Eiffel Tower has become a symbol of Paris throughout the world. ...