Neptune [SEP] time of discovery
. It is named after the Roman god of the sea and has the astronomical symbol ♆, a stylised version of the god Neptune's trident.
Neptune is not visible to the unaided eye and is the only planet in the Solar System found by mathematical prediction rather than by empirical observation. Unexpected changes in the orbit of Uranus led Alexis Bouvard to deduce that its orbit was subject to gravitational perturbation by an unknown planet. Neptune was subsequently observed with a telescope on 23 September 1846 by Johann Galle within a degree of the
(309239) 2007 RW10
, provisionally known as , is a temporary quasi-satellite of Neptune. Observed from Neptune, it would appear to go around it during one Neptunian year but it actually orbits the Sun, not Neptune.
Discovery, orbit and physical properties.
 was discovered by the Palomar Distant Solar System Survey on September 9, 2007, with precovery images from 1988 (also taken at Palomar). At the time of discovery, this minor body was believed to be a Neptune trojan, but