← Explore on the interactive map

Ole Rømer

Type Figure Region Denmark Time 1644–1710 Also known as Rømer

Ole Rømer (1644–1710) was a Danish astronomer. At the Paris Observatory, based on timing differences in the eclipses of Io, he demonstrated to the Ac…

Timeline

  1. 1644–1671Aarhus · JutlandAfter growing up in Aarhus he went to the University of Copenhagen, where he helped edit Tycho's manuscripts and assisted Jean Picard in determining the difference in longitude between Hven and Paris.
  2. 1672–1676Paris Observatory · ParisHe accompanied Picard to Paris and systematically timed the eclipses of Io at the Paris Observatory under Cassini's direction, serving longitude determination and satellite ephemerides.
  3. 1676–1681Paris · Île-de-FranceIn 1676 he predicted to the Paris Academy that the eclipses of Io would be about ten minutes later than the old tables indicated, and explained in the Journal des sçavans that light takes about 22 minutes to cross the diameter of Earth's orbit; Cassini refused to accept this fully, while Huygens and Newton adopted the finite speed of light.
  4. 1681–1710Copenhagen · ZealandRecalled home to become professor of astronomy at the University of Copenhagen, he built meridian instruments and successively held municipal posts such as chief of police and mayor, reforming weights, measures, and the calendar; he died in office in 1710.

Sources