Submitted by mossy2100 on Tue, 04/25/2017 - 01:27

Dates and datetimes

The standard notations for Utopian dates and datetimes are similar to the international standard ISO 8601 for Gregorian equivalents, with a few differences:

  • Martian mir numbers, dates, datetimes, and times are prefixed with ‘M’, to indicate Mars, and to distinguish them from Terran equivalents.
  • Mir numbers do not need to be zero-padded to a fixed number of digits. The current mir number (216 at the time of writing) has 3 digits, but this is written as M216, not M0216. When it reaches 1000, it will be M1000. This is for future-proofing. Eventually mir numbers will have 4 digits, 5 digits, and so on. (It’s a flaw in ISO 8601 that years must be expressed as exactly four digits, because the standard will not work from the year 10 000. The creators created a Y10K problem, which will affect many databases and systems.)
  • The first mir in the epoch is M0.
  • Negative mir numbers indicate mirs before the start of the epoch, e.g. M–100. There is no equivalent of BC/AD or BCE/CE notation.
  • As with Terran years, thousands separators are not used in mir numbers, e.g. M12345 (not M12,345 or M12.345 or M12 345).
  • The date separator character is ‘/’ (forward slash). On Earth we different date separators in different countries, including ‘’ (hyphen, dash, or minus sign), ‘/’ (forward slash), and ‘.’ (period or decimal point). The ISO 8601 standard uses the dash (e.g. “2016-12-06”). However, the hyphen and period characters have other meanings within the Mars datetime format, as a negative sign and a decimal point respectively, therefore we must choose an alternative for clarity. The forward slash is the most obvious choice, as it clearly indicates a date when used in this way. A different character could potentially be used, e.g. 216^17^22 or 216*17*22, but this might be tedious to write, less likely to be adopted, less obviously a date, and unclear as to meaning. The M prefix will prevent confusion with Terran dates better than an unusual separator.
  • As in ISO 8601, the date parts are arranged from most to least significant, i.e. M{mir}/{month}/{sol}, e.g. M216/17/08.
  • As in ISO 8601, month and sol parts of the date are zero-padded to 2 digits, e.g. M216/17/08.
  • Times are usually displayed with microsol resolution by showing the number of millisols to 3 decimal places. Both the number of millisols and microsols are zero-padded to 3 digits, e.g. 012.345, 888.222, 500.000.
  • As in ISO 8601, a date and time can be combined into a single datetime string using the ‘T' as a separator between the date and the time, e.g. M216/17/08T123.456.
  • When displayed without a date, Martian times can optionally be prefixed with ‘MT’ to distinguish them from ordinary numbers if necessary, e.g. MT012.345, MT567.222.
  • Times can also be shown with only millisol resolution, e.g. MT012, MT777.
  • If required, the timezone can be shown as the offset in decisols, in the range –5, –4, ... –1, +0, +1, ... +5, e.g. M216/17/08T123.456+3.
Uses of the format.
Display Format Example(s)
Mir M{mir} M216
Month M{mir}/{month} M216/17
Date M{mir}/{month}/{sol} M216/17/08
Time, low precision MT{mil} MT123
Time, high precision MT{mil}.{mic} MT123.456
Datetime, low precision M{mir}/{month}/{sol}T{mil} M216/17/08T123
Datetime, high precision M{mir}/{month}/{sol}T{mil}.{mic} M216/17/08T123.456
Datetime with timezone M{mir}/{month}/{sol}T{mil}.{mic}{offset} M216/17/08T123.456+3


{mir} = Mir as an integer (negative, 0, or positive), with no thousands separators.

{month} = Month as a zero-padded 2-digit integer in the range 01–24.

{sol} = Sol of the month as a zero-padded 2-digit integer in the range 01–28.

{mil} = Millisols as a zero-padded 3-digit integer in the range 000–999.

{mic} = Microsols as a zero-padded 3-digit integer in the range 000–999.

{offset} = Number of decisols offset for the timezone.

Comparing Earth times of day with Mars
Time of day/sol Earth Mars
Midnight; start of new day/sol. 00:00:00 MT000.000
Average time of sunrise; start of morning. 06:00:00 MT250.000
Noon; start of afternoon. 12:00:00 MT500.000
Average time of sunset; start of evening. 18:00:00 MT750.000

Long date format

The long date format looks like:

M{mir} {monthName} {sol}

For example:

M216 Tucana 24

The ‘M’ prefix in front of the mir indicates a Martian date, and eliminates confusion about which number refers to the mir and which to the sol.