3.7 KiB
| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Decimal time | 5/5 | https://en.wikipedia.org/wiki/Decimal_time | reference | science, encyclopedia | 2026-05-05T11:12:32.390542+00:00 | kb-cron |
== Scientific decimal time == Scientists often record time as decimal. For example, decimal days divide the day into 10 equal parts, and decimal years divide the year into 10 equal parts. Decimals are easier to plot than both (a) minutes and seconds, which uses the sexagesimal numbering system, (b) hours, months and days, which has irregular month lengths. In astronomy, the so-called Julian day uses decimal days centered on Greenwich noon.
Seconds in a decimal minute Since there are 60 seconds in a minute, a tenth part represents 60/10 = 6 seconds.
Minutes in a decimal hour Since there are 60 minutes in an hour, a tenth part represents 60/10 = 6 minutes.
Hours in a decimal day Since there are 24 hours in a day, a tenth part represents 24/10 = 2.4 hours (2 hours and 24 minutes).
Length of a decimal year Since there are about 365 days in a year, there are about 365/10 = 36.5 days in a tenth of a year. Hence the year 2020.5 represents the day 2 July 2020. More exactly, a "Julian year" is approximately 365.25 days long, so a tenth of the year is 36.525 days (36 days, 12 hours, 36 minutes).
These values, based on the Julian year, are most likely to be those used in astronomy and related sciences. A Gregorian year, which takes into account the 100 vs. 400 leap year exception rule of the Gregorian calendar, is 365.2425 days (the average length of a year over a 400–year cycle), resulting in 0.1 years being a period of 36.52425 days (3155695.2 seconds; 36 days, 12 hours, 34 minutes, 55.2 seconds).
== Other decimal times == Many people have proposed variations of decimal time, dividing the day into different numbers of units and subunits with different names. Most are based upon fractional days, so that one decimal time format may be easily converted into another, such that all the following are equivalent:
0.500 day 5 heures décimales @500 .beats Swatch Internet Time (see above) 50.0 kes or cés (centidays) 500 millidays 50.0% time as a percentage of the day 12:00 standard time Some decimal time proposals are based upon alternate units of metric time. The difference between metric time and decimal time is that metric time defines units for measuring time interval, as measured with a stopwatch, and decimal time defines the time of day, as measured by a clock. Just as standard time uses the metric time unit of the second as its basis, proposed decimal time scales may use alternative metric units. In the fictional Star Trek universe, each stardate increment represents one milliyear, with 78 years in 2401, counted from 2323. The decimal represents a fractional day. Thus, stardates are a composition of two types of decimal time. In 2023, 78 years earlier would be 1945.
== See also ==
== References ==
=== Notes ===
=== Sources === National Convention of the French Republic (1793) LE CALENDRIER RÉPUBLICAIN Textes officiels Décrets Relatifs à l'établissement de l'Ère Républicaine Archived 2013-03-17 at the Wayback Machine published by Philippe Chapelin 2002 Sizes, Inc. (2000) decimal time units Last revised 27 February 2004 Herschel, John (1849) Outlines of Astronomy Archived 2022-12-31 at the Wayback Machine published by Gallica 1995
== External links == Decimal Time by Kevin Gut - Website that shows the current decimal time and a converter to and from decimal time Decimal Time by Nabil Hunt - Shows local decimal time alongside conventional time Metric Clock by Paul Dunning / Shows the current local decimal time Decimal Time Clock & Calendar