==Notes====References====External links==* Short, uncluttered explanation by Ethan Siegel*Visualize Solar System at a given Epoch*The history of a velocity*Rømer and the Doppler principle*Proceeding of a Rømer Experiment for Schools from EAAE Summer Schools
* Short, uncluttered explanation by Ethan Siegel* Visualize Solar System at a given Epoch* The history of a velocity* Rømer and the Doppler principle* Proceeding of a Rømer Experiment for Schools from EAAE Summer Schools* Catalogus Stellarum Australium