On Nov. 21, 1676, the Danish astronomer Ole Rømer found the speed of light. Prior to Rømer figured it out, scientists believed that light journeys instantaneously, or definitely fast. When he was studying Jupiters moon Io, rømer negated this nearly by accident. He was trying to determine how long it takes Io to orbit Jupiter in hopes of utilizing it as a cosmic clock. He enjoyed Io disappear behind Jupiter and come back on the other side. He did this over and over every 42 hours for several years. This visualization shows a jet blasting from a black hole near the speed of light. Time behaves really oddly when things reach near light speed. (Image credit: NASA/JPL-Caltech) To his surprise, the timing of the eclipses was not constant. The eclipses happened 11 minutes early when Earth was closest to Jupiter. Likewise, when the 2 worlds were farthest away, the eclipses were 11 minutes behind schedule. Rømer found out the pattern and made an accurate forecast for Ios eclipse on Nov. 9, 1676. Then on Nov. 21, he took his findings to the Royal Academy of Sciences and described that a finite speed of light need to be responsible.Catch up on our entire “On This Day In Space” series on YouTube with this playlist. On This Day in Space Archive! Still not enough area? Dont forget to have a look at our Space Image of the Day, and on the weekends our Best Space Photos and Top Space News Stories of the week. Email Hanneke Weitering at [email protected] or follow her @hannekescience. Follow us @Spacedotcom and on Facebook..
21, 1676, the Danish astronomer Ole Rømer discovered the speed of light. When objects reach near light speed, time acts extremely oddly. Still not enough space?