{"slug": "christiaan-huygens", "label": "Christiaan Huygens", "wikipedia": "https://en.wikipedia.org/wiki/Christiaan_Huygens", "wikidata": "https://www.wikidata.org/wiki/Q39599", "qid": "Q39599", "description": "Dutch mathematician, physicist and astronomer (1629–1695)", "entries": 8, "years": 8, "span": [1655, 1690], "span_label": ["1655 CE", "1690 CE"], "topics": [{"title": "Science & Discovery", "count": 7}, {"title": "Culture & Society", "count": 1}], "related": [{"slug": "saturn", "label": "Saturn", "shared": 3}], "items": [{"year": 1655, "year_label": "1655 CE", "section": "Science & Discovery", "date": "March 25", "text": "March 25 – Saturn's largest moon, Titan, is discovered by Christiaan Huygens.", "cite": {"url": "https://en.wikipedia.org/w/index.php?oldid=1365983750#January–March", "title": "1655", "revid": 1365983750, "section": "Events › January–March"}}, {"year": 1656, "year_label": "1656 CE", "section": "Science & Discovery", "date": "December 25", "text": "December 25 – The pendulum clock is invented by Christiaan Huygens, so accurate that it only loses 10 seconds per day. Huygens will mention the date in a letter to Ismail Boulliau a year later.", "cite": {"url": "https://en.wikipedia.org/w/index.php?oldid=1372048661#October–December", "title": "1656", "revid": 1372048661, "section": "Events › October–December"}}, {"year": 1657, "year_label": "1657 CE", "section": "Science & Discovery", "date": null, "text": "Christiaan Huygens writes the first book to be published on probability theory, De ratiociniis in ludo aleae (\"On Reasoning in Games of Chance\").", "cite": {"url": "https://en.wikipedia.org/w/index.php?oldid=1366656979#Date_unknown", "title": "1657", "revid": 1366656979, "section": "Events › Date unknown"}}, {"year": 1659, "year_label": "1659 CE", "section": "Science & Discovery", "date": "July", "text": "July – Christiaan Huygens's important work on astronomy, Systema Saturnium, is published.", "cite": {"url": "https://en.wikipedia.org/w/index.php?oldid=1365986380#July–September", "title": "1659", "revid": 1365986380, "section": "Events › July–September"}}, {"year": 1671, "year_label": "1671 CE", "section": "Science & Discovery", "date": "October 25", "text": "October 25 – Italian-born French astronomer Giovanni Domenico Cassini discovers Iapetus, the second known moon of the planet Saturn. Christiaan Huygens had discovered the Saturnian moon Titan on March 25, 1655.", "cite": {"url": "https://en.wikipedia.org/w/index.php?oldid=1365991065#October–December", "title": "1671", "revid": 1365991065, "section": "Events › October–December"}}, {"year": 1672, "year_label": "1672 CE", "section": "Science & Discovery", "date": "December 23", "text": "December 23 – French astronomer Giovanni Domenico Cassini discovers Rhea, a previously-unknown satellite of the planet Saturn. Rhea is the second-largest overall, and the third moon of Saturn to be discovered by Earth astronomers, Titan having been found by Christiaan Huygens on March 25, 1655 and Iapetus by Cassini on October 25, 1671.", "cite": {"url": "https://en.wikipedia.org/w/index.php?oldid=1365992116#October–December", "title": "1672", "revid": 1365992116, "section": "Events › October–December"}}, {"year": 1675, "year_label": "1675 CE", "section": "Science & Discovery", "date": "February 25", "text": "February 25 – Netherlands scientist Christiaan Huygens files drawings of his invention of the balance spring, the key component to the accuracy of portable clocks and pocket watches, in a letter to the Journal des Sçavants.", "cite": {"url": "https://en.wikipedia.org/w/index.php?oldid=1365992546#January–March", "title": "1675", "revid": 1365992546, "section": "Events › January–March"}}, {"year": 1690, "year_label": "1690 CE", "section": "Culture & Society", "date": null, "text": "Dutch polymath Christiaan Huygens publishes his book Treatise on Light. The book is considered a pioneering work of theoretical and mathematical physics.", "cite": {"url": "https://en.wikipedia.org/w/index.php?oldid=1369486553#Date_unknown", "title": "1690", "revid": 1369486553, "section": "Events › Date unknown"}}]}