Jc3s5h added a comment. In https://phabricator.wikimedia.org/T94064#1296543, @daniel wrote:
> @mkroetzsch precise dates for prehistoric times may be useful for > astronomical events. These could/should use a different calendar model > though, such as https://en.wikipedia.org/wiki/Julian_day (Q14267), see > T59704: Support Julian Date (astronomy) > <https://phabricator.wikimedia.org/T59704> To support dates of prehistoric astronomical events, the issue isn't whether to use the Julian day, the proleptic Julian calendar, or the proleptic Gregorian calendar. The issue is that the theories of motion of the Solar System, use time scales such as Terrestrial Time or Barycentric Coordinate Time. These time scales use seconds of equal length, very similar to the seconds produced by atomic clocks. But calendars conventionally count actual solar days. Because the rate of rotation of the Earth is steadily decreasing **January 3, 10,000 BC, Julian proleptic calendar modified to observe Terrestrial Time** would be approximately **January 1, 10,000, Julian proleptic calendar**. The actual rotation rate of the Earth is not well known enough to create a definitive conversion between calendar dates and Terrestrial Time (and other similar timescales) dates. So support of prehistoric astronomical events would require support for multiple time scales; one or more for actual observed solar days, and others where the length of a day is close to 86,400 atomic seconds. TASK DETAIL https://phabricator.wikimedia.org/T94064 EMAIL PREFERENCES https://phabricator.wikimedia.org/settings/panel/emailpreferences/ To: Smalyshev, Jc3s5h Cc: thiemowmde, Jc3s5h, Lydia_Pintscher, Denny, Manybubbles, daniel, mkroetzsch, Smalyshev, JanZerebecki, Aklapper, jkroll, Wikidata-bugs, Jdouglas, aude _______________________________________________ Wikidata-bugs mailing list [email protected] https://lists.wikimedia.org/mailman/listinfo/wikidata-bugs
