* [http://www.calctool.org/CALC/phys/astronomy/planet_orbit CalcTool: Orbital period of a planet calculator]. Has wide choice of units. Requires JavaScript.
* [http://orinetz.com/planet/animatesystem.php?sysid=QUQTS2CSDQ44FDURR3XD6NUD6&orinetz_lang=1 Browser Based Three Dimension Simulation of Orbital Motion]. Objects and distance are drawn to scale. Run on JavaScript-enabled browser such as Internet Explorer, Mozilla Firefox and Opera.
* [http://www.phy.hk/wiki/englishhtm/Motion.htm Java simulation on orbital motion]. Requires Java.
* [http://www.ncdc.noaa.gov/paleo/forcing.html NOAA page on Climate Forcing Data] includes (calculated) data on Earth orbit variations over the last 50 million years and for the coming 20 million years
* [http://www.braeunig.us/space/orbmech.htm Orbital Mechanics] (Rocket and Space Technology)
* [http://astrobiology.ucla.edu/OTHER/SSO/ Orbital simulations by Varadi, Ghil and Runnegar (2003)] provide another, slightly different series for Earth orbit eccentricity, and also a series for orbital inclination. Orbits for the other planets were also calculated, by {{cite journal | author=F. Varadi, B. Runnegar, M. Ghil | title=Successive Refinements in Long-Term Integrations of Planetary Orbits | journal=The Astrophysical Journal | volume=592 | year=2003 | pages=620–630|doi=10.1086/375560 | bibcode=2003ApJ...592..620V}}, but only the [http://www.astrobiology.ucla.edu/OTHER/SSO/Misc/ eccentricity data for Earth and Mercury] su dostupni online.
* {{cite web|last=Merrifield|first=Michael|title=Orbits (uključujući prvo orbitiranje sa ljudskom posadom)|url=http://www.sixtysymbols.com/videos/orbit.htm|work=Sixty Symbols|publisher=[[Brady Haran]] za [[University of Nottingham]]}}
