Nẹ́ptúnù ni kejo ti eyi tojinajulo si Orun ninu Sistemu Orun. Hamilton, Calvin J. (August 4, 2001). "Neptune". Views of the Solar System. Retrieved August 13, 2007.  Walter, Elizabeth (April 21, 2003). Cambridge Advanced Learner's Dictionary (2nd ed.). Cambridge University Press. ISBN 0-521-53106-3.  Yeomans, Donald K. (July 13, 2006). "HORIZONS System". NASA JPL. Retrieved August 8, 2007. —At the site, go to the "web interface" then select "Ephemeris Type: Elements", "Target Body: Neptune Barycenter" and "Center: Sun". Orbital elements refer to the barycentre of the Neptune system, and are the instantaneous osculating values at the precise J2000 epoch. Barycentre quantities are given because, in contrast to the planetary centre, they do not experience appreciable changes on a day-to-day basis from to the motion of the moons. Àṣìṣe ìtọ́kasí: Invalid <ref> tag; no text was provided for refs named fact2 Seligman, Courtney. "Rotation Period and Day Length". Retrieved August 13, 2009.