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Various schemes have been used or proposed to keep track of time and date on the planet Mars independently of Earth time and calendars. Mars is the fourth planet from the Sun in the solar system, named after the Roman god of war (the counterpart of the Greek Ares), on account of its blood red color as viewed in the night sky. ...
Mars has an axial tilt and a rotation period similar to those of Earth. Thus it experiences seasons of spring, summer, autumn and winter much like Earth, and its day is about the same length. Its year, however, is almost twice as long as Earth's, and its orbital eccentricity is considerably larger, which means among other things that the lengths of various Martian seasons differ considerably, and sundial time can diverge from clock time much more than on Earth. In astronomy, Axial tilt is the inclination angle of a planets rotational axis in relation to a perpendicular to its orbital plane. ...
Adjectives: Terrestrial, Terran, Telluric, Tellurian, Earthly Atmosphere Surface pressure: 101. ...
(This page refers to eccitricity in astrodynamics. ...
Keeping track of time of day The length of a Martian sidereal day is 24h 37m 22.663s in terms of Earth hours, and the length of its solar day is 24h 39m 35.244s (the latter is known as a sol, more precisely 88,775.24409 seconds). The corresponding values for Earth are 23h 56m 04.2s and 24h 00m 00.002s, respectively. This yields a conversion factor of 1.027346 sols/day. Thus Mars's solar day is only about 2.7% longer than Earth's. On a prograde planet like the Earth, the sidereal day is shorter than the solar day. ...
Solar time is based on the idea that, when the sun reaches its highest point in the sky, it is noon. ...
Because this is considered "close enough," a convention used by all the spacecraft lander projects to date has been to keep track of local solar time using a "24:60:60" clock, but on which the hours, minutes and seconds are "stretched" to 2.7% longer than their standard durations. Alternative clocks for Mars have been proposed, but no mission has chosen to use such. These include a metric time schema, with "millidays" and "centidays", and an extended which uses standard units but which counts to 24hr 39m 35s before ticking over to the next day. Metric time is the measure of time interval using the metric system, which defines the second as the base unit of time, and multiple and submultiple units formed with metric prefixes, such as kiloseconds and milliseconds. ...
Kim Stanley Robinson's influential Mars Trilogy includes a system whereby the clocks work at a similar rate as those on Earth, but freeze at midnight for 39.5 minutes. As the fictional colonization of Mars progresses, this "timeslip" becomes a sort of witching hour, a time when inhibitions can be shed and the emerging identity of Mars as a separate entity from Earth is celebrated. Kim Stanley Robinson at the 63rd World Science Fiction Convention in Glasgow, August 2005 Kim Stanley Robinson (born March 23, 1952) is an American science fiction writer, probably best known for his award-winning Mars trilogy. ...
The Mars trilogy is a series of award-winning science fiction novels by Kim Stanley Robinson, chronicling the settlement and terraforming of the planet Mars. ...
Mars Mars is the focus of much speculation and serious study about possible human colonization. ...
In European folklore, the witching hour is the time when supernatural creatures such as witches, demons and ghosts are thought to be at their most powerful, and black magic at its most effective. ...
It is important to be aware of local solar time for purposes of planning the daily activities of Mars landers. Daylight is needed for the solar panels. Also, temperatures will rise and fall in very rapid synchronicity with the Sun because, unlike on Earth, the thin atmosphere and lack of water do very little to buffer temperature fluctuations. The Sun (Latin: Sol) is the star at the center of the Solar System. ...
As on Earth, on Mars there is also an equation of time that represents the difference between sundial time and clock time as displayed by a Martian timepiece (such timepieces have been made for NASA employees [1]). The equation of time is illustrated by an analemma. Because of Mars' greater orbital eccentricity, its equation of time is much larger than that of Earth: on Mars, the Sun can run 50 minutes slower or 40 minutes faster than a Martian clock (on Earth, the corresponding figures are 14min 22sec slower and 16min 23sec faster). The analemma on Mars is not figure-8 shaped as it is on Earth. ...
The analemma on Mars is not figure-8 shaped as it is on Earth. ...
The analemma photographed, looking east in the northern hemisphere. ...
Mars is the fourth planet from the Sun in the solar system, named after the Roman god of war (the counterpart of the Greek Ares), on account of its blood red color as viewed in the night sky. ...
During the course of the year, the time as read from a sundial can run ahead of clock time by as much as 16 min 33 s (around October 31–November 1) or fall behind by as much as 14 min 6 s (around February 11–12). ...
The analemma photographed, looking east in the northern hemisphere. ...
Mars has a prime meridian, defined as passing through the small crater Airy-0. In the future, perhaps Mars could have time zones defined at regular intervals from the prime meridian, as on Earth. However, for the time being, there is no need to co-ordinate the activities of the various landers, so each lander uses its own timezone (some approximation of local solar time), as cities did on Earth before the introduction of standard time in the 19th century. Location of the Prime Meridian Prime Meridian in Greenwich The Prime Meridian, also known as the International Meridian or Greenwich Meridian, is the meridian (line of longitude) passing through the Royal Greenwich Observatory, Greenwich, England — it is the meridian at which longitude is 0 degrees. ...
Airy-0 is a crater on Mars whose location defines the position of the prime meridian of that planet. ...
A time zone is a region of the Earth that has adopted the same standard time, usually referred to as the local time. ...
Universal Time (UT) is a timescale based on the rotation of the Earth. ...
Note that the modern standard for measuring longitude on Mars is "planetocentric longitude", which is measured from 0°–360° East and measures angles from the center of Mars. The older "planetographic longitude" was measured from 0°–360° West and used coordinates mapped onto the surface. [2]
Coordinated Mars Time (MTC) MTC is a Mars analog to Universal Time (UT) on Earth. It is defined as the mean solar time at Mars's prime meridian (i.e., at the centre of the crater Airy-0). The name "MTC" is intended to parallel the Terran Coordinated Universal Time (UTC), but this is somewhat misleading: what distinguishes UTC from other forms of UT is its leap seconds, but MTC does not use any such scheme. MTC is more closely analogous to UT1. Universal Time (UT) is a timescale based on the rotation of the Earth. ...
Airy-0 is a crater on Mars whose location defines the position of the prime meridian of that planet. ...
Coordinated Universal Time (UTC) is a high-precison atomic time standard. ...
Use of the term "MTC" as the name of a planetary standard time for Mars first appeared in the Mars24 [3] sunclock coded by the NASA Goddard Institute for Space Studies. It replaced Mars24's previous use of the term "Airy Mean Time" (AMT), which was a direct parallel of Greenwich Mean Time (GMT). In an astronomical context, "GMT" is a deprecated name for Universal Time, or sometimes more specifically for UT1. Goddard Institute for Space Studies building. ...
Time zones of Europe: Light colours indicate countries not observing summer time Greenwich Mean Time (Media:Example. ...
AMT has not yet been employed in official mission timekeeping. This is partially attributable to uncertainty regarding the position of Airy-0 (relative to other longitudes), which meant that AMT couldn't be realised as accurately as local time at points being studied. At the start of the Mars Exploration Rover missions, the positional uncertainty of Airy-0 corresponded to roughly a 20 second uncertainty in realising AMT. Artists Concept of Rover on Mars (credit: Maas Digital LLC) NASAs Mars Exploration Rover (MER) Mission is an ongoing unmanned Mars exploration mission, commenced in 2003, that sent two robotic rovers Spirit and Opportunity to explore the Martian surface and geology. ...
Timezones Each lander mission so far has used its own timezone, approximating local solar time at the landing location. Of the five successful Mars landers to date, four employed variants of local mean solar time (LMST) for the lander site while the fifth (Mars Pathfinder) used local true solar time (LTST). [4] [5] The Mars Pathfinder was launched on December 4, 1996 by NASA aboard a Delta II just a month after the Mars Global Surveyor was launched. ...
Mars Pathfinder used local apparent solar time at the landing location. Its timezone was AAT-02:13:01, where "AAT" is Airy Apparent Time, meaning apparent solar time at Airy-0.
The two Mars Exploration Rovers don't use either LMST or LTST of the landing points. They picked a time scale that would match apparent solar time in the operational area about halfway through the nominal 90-sol mission. The time scales are uniform in the sense of mean solar time (they are actually mean time of some longitude), and are not adjusted as the rovers travel. (The rovers have travelled distances that make a few seconds difference to local solar time.) Spirit uses AMT+11:00:04. Mean solar time at its landing site is AMT+11:41:55. Opportunity uses AMT-01:01:06. Mean solar time at its landing site is AMT-00:22:06. Neither rover is likely to ever reach the longitude at which its mission time scale matches local mean time. Artists Concept of Rover on Mars (credit: Maas Digital LLC) NASAs Mars Exploration Rover (MER) Mission is an ongoing unmanned Mars exploration mission, commenced in 2003, that sent two robotic rovers Spirit and Opportunity to explore the Martian surface and geology. ...
With the location of Airy-0 now known much more precisely than when these missions landed, it is technically feasible for future missions to use a convenient offset from Airy Mean Time, rather than completely non-standard timezones. It remains to be seen whether this will in fact be done.
Keeping track of sols When a spacecraft lander begins operations on Mars, it keeps track of the passing Martian days (sols) by a simple numerical count. The two Viking missions defined the sol on which each lander touched down as "Sol 0" for each mission, but subsequent missions (i.e., Mars Pathfinder and the two Mars Exploration Rovers) instead defined touch down as "Sol 1". However, it appears that the Mars Phoenix project has chosen to commence counting with "Sol 0"[6]. Conceptual drawing The Phoenix is a NASA Mars lander scheduled to launch in August 2007 during a 22 day launch window. ...
Although these lander missions have twice occurred in pairs, no effort was made to synchronize the sol counts of the two landers within each pair. Thus, for example, although Spirit and Opportunity operated simultaneously on Mars, when Opportunity landed on Mars and started its count from Sol 1, the mission date for Spirit had already reached Sol 22.
On Earth, astronomers often prefer to use Julian dates for timekeeping purposes. This is simply a sequential count of days, bypassing the complications of calendars. One proposed counterpart on Mars is the Mars Sol Date, or MSD, which is a running count of sols since approximately December 29, 1873 (in principle any start date (known as the "epoch") could be used; however, it should be far enough in the past that all historically recorded events occur after the epoch). The Julian day or Julian day number (JDN) is the number of days that have elapsed since 12 noon Greenwich Mean Time (UT or TT) on Monday, January 1, 4713 BC (in the proleptic Julian calendar; or November 24, 4714 BC in the proleptic Gregorian calendar). ...
December 29 is the 363rd day of the year (364th in leap years) in the Gregorian calendar, with 2 days remaining. ...
1873 (MDCCCLXXIII) was a common year starting on Wednesday (see link for calendar). ...
In astronomy, an epoch is a moment in time for which celestial coordinates or orbital elements are specified. ...
The Mars Sol Date is defined mathematically as MSD = (Julian date using International Atomic Time - 51549.0 + k)/1.02749125 + 44796.0, where k is a small correction of approximately 0.00014d (or 12sec) due to uncertainty in the exact geographical position of the prime meridian at Airy-0 crater. International Atomic Time (TAI, from the French name Temps Atomique International) is a high-precision atomic time standard that tracks proper time on Earths geoid. ...
At some point in the future, Mars may need a Julian-date-like count of days, and the MSD is as good a candidate as any (although some prefer an epoch back around 1608). However, MSD is not really used yet, as there was no effort made to synchronize the count of successive sols between Spirit and Opportunity to make them use a common count. In any case, Spirit and Opportunity are on opposite hemispheres, so when it is daylight for one it is night for the other, and they carry out activities completely independently, so there would be no practical advantage in a common sol count. Events March 18 - Sissinios formally crowned Emperor of Ethiopia May 14 - Protestant Union founded in Auhausen. ...
The word "yestersol" was coined by NASA to refer to the previous sol (the Mars version of "yesterday") and came into fairly wide use within that organization during the Mars Exploration Rover Mission of 2003. It was even picked up and used by the press. Other neologisms such as "tosol" (for "today") and "nextersol" or "morrowsol" (for "tomorrow") have been less successful. Artists Concept of Rover on Mars (credit: Maas Digital LLC) NASAs Mars Exploration Rover (MER) Mission is an ongoing unmanned Mars exploration mission, commenced in 2003, that sent two robotic rovers Spirit and Opportunity to explore the Martian surface and geology. ...
2003 (MMIII) was a common year starting on Wednesday of the Gregorian calendar. ...
Keeping track of calendar dates Of course, for most day-to-day activities on Earth, people don't use Julian dates. They use the Gregorian calendar, which despite its various complications is quite useful. By looking at a Gregorian calendar date you immediately know whether that date is an anniversary of any other date, and you know whether the date is in winter or spring, and you can easily calculate the number of years between two dates. It is much less practical to do this with Julian dates. The Gregorian calendar is the most widely used calendar in the world. ...
For similar reasons, if it is ever necessary to schedule and co-ordinate activities on a large scale across the surface of Mars it would be necessary to agree on a calendar. One proposal put forth for such a thing is the Darian calendar. It has 24 "months", to accommodate the longer Martian year while keeping the notion of a "month" that is reasonably similar to the length of an Earth month. On Mars, a "month" would have no relation to the orbital period of any moon of Mars, since Phobos and Deimos orbit in about 7 hours and 30 hours respectively. However the Earth's Moon would generally be visible to the naked eye along with the Earth when both were above the horizon at night, and the time it takes for the Moon to move from maximum separation in one direction to the other and back as seen from Mars is close to a Lunar month. The Darian Calendar is a system of time-keeping designed to serve the needs of any possible future human settlers on the planet Mars. ...
Phobos (IPA or , Greek Φόβος: Fright), is the larger and innermost of Mars two moons (the other being Deimos), and is named after Phobos, son of Ares (Mars) from Greek Mythology. ...
Deimos (IPA or ; Greek Δείμος: Dread), is the smaller and outermost of Mars’ two moons, named after Deimos from Greek Mythology. ...
In lunar calendars, a lunar month is the time between two successive similar syzygies (new moons or full moons). ...
Length of Martian year The length of a sidereal year on Mars is about 686.98 Earth solar days, or 668.5991 sols. This is the time it takes for Mars to complete one orbit around the Sun. However, as on Earth, this is not the quantity that is needed for calendar purposes. Rather, the tropical year would be used because the tropical year gives the best match to the progression of the seasons. The length of the tropical year is slightly shorter than the sidereal year due to the precession of Mars' rotational axis. The length of the precession cycle on Mars is 93,000 Martian years, or 175,000 Earth years, which is considerably longer than the precession cycle of Earth. The length of the precession cycle in tropical years can be computed by dividing the difference between the sidereal year and tropical year by the length of the tropical year. The sidereal year is the time for the Sun to return to the same position in respect to the stars of the celestial sphere. ...
A tropical year is the length of time that the Sun, as viewed from the Earth, takes to return to the same position along the ecliptic (its path among the stars on the celestial sphere). ...
Precession of a gyroscope Precession refers to a change in the direction of the axis of a rotating object. ...
The tropical year is not a single value, but can vary according to which point is used as the starting point to measure the length of the year. The tropical year can be measured in relation to an equinox or solstice, or can be the mean of various possible years including the March (northward) equinox year, June (northern) solstice year, the September (southward) equinox year, the December (southern) solstice year and other such years. The length variation is due to the effects of Kepler's second law of planetary motion. The length of the Gregorian calendar is measured using the March equinox year. Johannes Keplers primary contributions to astronomy/astrophysics were his three laws of planetary motion. ...
A tropical year is the length of time that the Sun, as viewed from the Earth, takes to return to the same position along the ecliptic (its path among the stars on the celestial sphere). ...
On Earth the variation in the lengths of the tropical years is usually glossed over because the effect is not that important; however, on Mars, the differences are significantly larger. On Mars, the northward equinox year is 668.5907 sols, the northern solstice year is 668.5880 sols, the southward equinox year is 668.5940 sols, and the southern solstice year is 668.5958 sols. Averaging out over an entire orbital period gives a Martian tropical year of 668.5921 sols. Note that it is not possible to refer to Martian equinoxes and solstices unambiguously by using seasonal references alone, because like Earth, Mars has two hemispheres with opposite seasons. Thus, the location of the Sun (for solstices) and direction of motion of the Sun (for equinoxes) is used to remove this ambiguity.
Intercalation Any calendar must use intercalation (leap years) to make up for the fact that a year is not equivalent to an integer number of days. Without intercalation, the year will accumulate errors over time. Most designs for Martian calendars intercalate single days, but a few designs exist that employ an intercalary week. Intercalation is the insertioffn of an extra day, week or month into some calendar years to make the calendar follow the seasons. ...
A leap year (or intercalary year) is a year containing an extra day (or, in case of lunisolar calendars, an extra month) in order to keep the calendar year synchronised with the astronomical or seasonal year. ...
For the Gregorian calendar, the leap-year formula is every 4th year except for every 100th year except for every 400th year, which produces an average calendar year length of 365.2425 solar days. This is close enough to the March equinox year. On Mars, a similar intercalation scheme for leap years would be needed. However, the exact intercalation scheme would depend on exactly which year was adopted for calendar purposes: calendars based on the southern solstice year or on the northward equinox year would differ by one sol in as little as two hundred or so Martian years.
The Darian calendar uses the northward equinox year length of 668.5907 sols as the basis of its intercalation scheme.
Simple Mars Clock (UTC to MTC) ...
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OpenOffice. ...
See also This article presents information and images about viewing astronomical phenomena from the planet Mars. ...
The Darian Calendar is a system of time-keeping designed to serve the needs of any possible future human settlers on the planet Mars. ...
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