<p>On Dec. 20, 1900, astronomer Michel Giacobini spotted a 10th-magnitude comet while working at Nice Observatory, in France. Calculations following his discovery suggested the comet had an orbital period of a bit less than seven years. When German astronomer Ernst Zinner rediscovered the comet on Oct. 23, 1913, happening across it by accident while observing<a class="more-link" href="https://www.astronomy.com/today-in-the-history-of-astronomy/dec-20-1900-the-discovery-of-21p-giacobini-zinner/">Continue reading <span class="screen-reader-text">"Dec. 20, 1900: The discovery of 21P/Giacobini-Zinner"</span></a></p>
<p>The post <a href="https://www.astronomy.com/today-in-the-history-of-astronomy/dec-20-1900-the-discovery-of-21p-giacobini-zinner/">Dec. 20, 1900: The discovery of 21P/Giacobini-Zinner</a> appeared first on <a href="https://www.astronomy.com">Astronomy Magazine</a>.</p>
On Dec. 20, 1900, astronomer Michel Giacobini spotted a 10th-magnitude comet while working at Nice Observatory, in France. Calculations following his discovery suggested the comet had an orbital period of a bit less than seven years. When German astronomer Ernst Zinner rediscovered the comet on Oct. 23, 1913, happening across it by accident while observingContinue reading “Dec. 20, 1900: The discovery of 21P/Giacobini-Zinner”
The post Dec. 20, 1900: The discovery of 21P/Giacobini-Zinner appeared first on Astronomy Magazine.