The red planet is the second name of Mars, which is quite close to the Earth. It is quite possible to observe the "neighbor" in the starry sky without a telescope.
Mars related to Earth group, is the fourth planet from the Sun. For comparison: the Earth occupies the third position in our solar system.
The red planet is our "neighbor"
The name "red" is primarily associated with its shade.
Due to the high content of iron oxides, the color of its surface is slightly reddish. As for the Earth, it is almost twice. The diameter of the planet is about half that of the Earth.
How long is a day on Mars?
The period of revolution of Mars around the Sun is 687 Earth days. That is, a year on Mars lasts almost twice as long as on Earth.
This is due to the fact that the distance to it is 1.62 times greater than from us to the Sun, and the period of revolution, of course, takes longer.
How long is a day on Mars? The duration of a day on Mars is quite close to that on Earth. Only this planet of ours solar system this period is as close as possible to us in comparison with the rest.
Regarding the duration, the day on Mars in hours familiar to our understanding will be 24 hours 37 minutes.
This indicator slightly exceeds the Earth day. The reason for how long a day lasts on Mars is, first of all, the speed of rotation of the Red Planet around its axis.
The length of the day on the planets of our solar system
The length of a day depends directly on the distance to the Sun and the speed of rotation around its own axis of each planet. A distinction is made between sidereal and solar days.
The magnitude of the difference between them depends on a combination of two factors - these are the periods of revolution around the Sun and revolution around its axis.
Consider the length of the day and year on other planets and compare with how long the day lasts on Mars and Earth.
The first and most is Mercury. A sidereal day is 59 Earth days, and a solar day is about 176.
As for Venus, due to its rotation in the opposite direction, sidereal days have a duration of 223 Earth days, and solar days are 117 days.
The Earth, on the other hand, has 24 hours in a solar day, the sidereal day is slightly shorter and is 23 hours 56 minutes.
The length of a day on Mars, stellar and solar, is similar to that on Earth. And they are respectively 24 hours 37 minutes and 24 hours and 40 minutes. That is, a day on Mars lasts 24 hours and 40 minutes.
As for the giant planets, on Jupiter it is almost ten hours, on Saturn - about 10 hours and 34 minutes. On Neptune - about 16 hours, and on Uranus - 17 hours and 15 minutes. The difference between solar and sidereal days on these planets is insignificant. This is due to the long period of revolution around the Sun.
As we can see, of all the planets in duration, in comparison with the Earth, Mars is the most similar.
A day on Mars, just like on our planet, is four minutes longer than a sidereal day.
On other planets, the difference is more significant, such a great similarity is not observed.
A day on Mars is the same as on Earth
In 2023, it is planned. This time, unlike conventional probes exploring the planet, people will fly on board the spacecraft.
This rather complicated mission is associated with the fact that the living conditions for people are much more difficult than on their native planet, and going for a walk in open space is impossible without protective equipment.
One of the issues for the adaptation of new Martian inhabitants is the body's reaction to how long a day lasts on Mars, in contrast to Earth conditions.
Will there be a full-fledged biological adaptation? According to physiologists, such a small difference of 37 minutes will be quite easily perceived by the settlers.
Many difficulties are expected, but, perhaps, despite Mars, which is so similar to ours, it will remind the astronauts of their home. No wonder the Red Planet is called the Earth's twin. Its likeness is great, but habitability is minimal.
Against the background of high levels of radiation to protect the settlers, it is planned to build residential complexes specially designed to protect against rather harsh conditions.
There is practically no atmosphere on Mars, increased rarefaction. The planet's air contains mainly carbon dioxide.
As for the climate, it is quite severe. At the equator in the summer, the temperature rises to a maximum of +27 degrees Celsius.
Thanks to this, the change of seasons is similar to the usual local conditions. But still, a year on Mars is almost twice as long as the earth and is almost 687 days.
Based on how long a day lasts on Mars, and from the total number of days in a Martian year, we get that the first settlers will see the Sun during the Martian year 668 times.
astronauts of the future
In this regard, the organizers and scientists of the mission have one more problem, which is technically almost solved. It is connected with the synchronization of our and Martian time. The scientific term "Sol" refers to a day on Mars or the length of a day.
This is how the new inhabitants of Mars will name their day and say that two or three sols have passed. Well, let's hope that such a grandiose mission will be successful and open a new interplanetary era of the future.
More strictly, this is the time interval between two similar (upper or lower) culminations (passing through the meridian) of the center of the Sun at a given point on the Earth (or other celestial body).
Encyclopedic YouTube
1 / 3
Leap year and sidereal day problems
More about time
Subtitles
Solar day on Earth
Fluctuations in the length of the solar day
The mean solar day is not subject to periodical changes like a true solar day, but their duration changes monotonously due to the change in the period of the axial rotation of the Earth and (to a lesser extent) with the change in the length of the tropical year, increasing by about 0.0017 seconds per century. Thus, the duration of the mean solar day at the beginning of 2000 was equal to 86400.002 SI seconds. It should be noted that here the SI second, determined using an intra-atomic periodic process, is indicated as a unit of measurement, and not the mean solar second, which by definition is equal to 1/86,400 of a mean solar day and, therefore, is also not constant.
Introduction of amendments
Although the average solar day is not, strictly speaking, an invariable unit of time, but everyday life people are connected to them. In connection with the accumulation of a correction to the length of the day in mean solar time with respect to uniform atomic time, sometimes it is necessary to add the so-called leap second to the UTC atomic scale in order to restore the binding of this scale to the solar time scale. Theoretically, the subtraction of a leap second is also possible, since the rotation of the Earth, in principle, does not have to constantly slow down.
Solar day on other planets and satellites
Moon
The average solar day on the Moon is equal to the average synodic month (the average interval between two identical phases of the Moon, for example, full moons) - 29 days 12 hours 44 minutes 2.82 seconds. The true solar day can deviate from the average by 13 hours in both directions, which is associated both with the uneven movement of the Earth in its orbit, and with the inclination of the Moon's orbit to the ecliptic, with the ellipticity of its orbit and with the inclination of the axis of rotation of the Moon to the plane of the orbit (see also libration).
Others On gas giants that do not have a solid surface, solar days depend on latitude - the atmosphere rotates at different speeds at different latitudes.
Mercury goes around the Sun in 87.97 days, and makes a complete revolution around its axis in 58.65 days (these periods are related as 3: 2). The average time interval between the two upper culminations of the Sun on this planet is 176 days, which is equal to two of its years. Interestingly, when it is near the perihelion, the Sun for an observer on the surface of the planet can move in the opposite direction for 8 days, therefore, strictly speaking, linking the definition of a solar day to the climax in this case is not quite correct.
On Venus, whose sidereal period of revolution on its axis is 243 days - longer than the orbital period (224.7 days), the average solar day is approximately 116.7 days (due to the rotation in the opposite direction)
On Mars, the average solar day is only slightly longer than Earth's. They are equal to 24 h 39 min 35.244 s.
On Jupiter, a day is 9 hours 55 minutes 40 seconds, on Saturn 10 hours 34 minutes 13 seconds. A day on Uranus is 17 hours 14 minutes 24 seconds, and on Neptune 15 hours 57 minutes 59 seconds.
In Pluto, due to its extreme remoteness from the Sun (and, consequently, the smallness of the angular orbital velocity), the average solar day is almost equal to the rotation period: 6 days 9 hours 17 minutes 36 seconds.
Notes
Here on Earth, we tend to take time for granted, never thinking that the step in which we measure it is rather relative.
For example, how we measure our days and years is the actual result of our planet's distance from the Sun, the time it takes to complete an orbit around it, and rotate around its own axis. The same is true for other planets in our solar system. While we earthlings calculate a day in 24 hours from dawn to dusk, the length of one day on another planet is significantly different. In some cases, it is very short, while in others, it can last more than a year.
Day on Mercury:
Mercury is the closest planet to our Sun, ranging from 46,001,200 km at perihelion (the closest distance to the Sun) to 69,816,900 km at aphelion (farthest). Mercury rotates on its axis in 58.646 Earth days, which means that a day on Mercury takes about 58 Earth days from dawn to dusk.
However, it takes Mercury only 87,969 Earth days to go around the Sun once (in other words, the orbital period). This means that a year on Mercury is equivalent to approximately 88 Earth days, which in turn means that one year on Mercury lasts 1.5 Mercury days. Moreover, the northern polar regions of Mercury are constantly in shadow.
This is due to its 0.034° axial tilt (compared to Earth's 23.4°), which means that Mercury does not experience extreme seasonal changes where days and nights can last for months, depending on the season. It is always dark at the poles of Mercury.
Day on Venus:
Also known as Earth's twin, Venus is the second closest planet to our Sun, ranging from 107,477,000 km at perihelion to 108,939,000 km at aphelion. Unfortunately, Venus is also the slowest planet, this fact is obvious when you look at its poles. Whereas the planets in the solar system experienced flattening at the poles due to rotational speed, Venus did not survive it.
Venus rotates at only 6.5 km/h (compared to Earth's rational speed of 1670 km/h), which results in a sidereal rotation period of 243.025 days. Technically, this is minus 243.025 days, since Venus's rotation is retrograde (i.e. rotation in the opposite direction of its orbital path around the Sun).
Nevertheless, Venus still rotates around its axis in 243 Earth days, that is, a lot of days pass between its sunrise and sunset. This may seem strange until you know that one Venusian year is 224.071 Earth days long. Yes, Venus takes 224 days to complete its orbital period, but more than 243 days to go from dawn to dusk.
So one day of Venus is a little more than a Venusian year! It is good that Venus has other similarities with the Earth, but this is clearly not a daily cycle!
Day on Earth:
When we think of a day on Earth, we tend to think it's just 24 hours. In truth, the sidereal period of the Earth's rotation is 23 hours 56 minutes and 4.1 seconds. So one day on Earth is equivalent to 0.997 Earth days. Oddly enough, again, people prefer simplicity when it comes to time management, so we round up.
At the same time, there are differences in the length of one day on the planet depending on the season. Due to the tilt of the earth's axis, the amount of sunlight in some hemispheres will change. The most striking cases occur at the poles, where day and night can last for several days and even months, depending on the season.
At the North and South Poles in winter, one night can last up to six months, known as "Polar Night". In summer, the so-called “polar day” will begin at the poles, where the sun does not set for 24 hours. It's actually not as easy as one would like to imagine.
Day on Mars:
In many ways, Mars can also be called Earth's twin. Add seasonal fluctuations and water (albeit in frozen form) to the polar ice cap, and a day on Mars is pretty close to Earth. Mars makes one revolution on its axis in 24 hours. 
37 minutes and 22 seconds. This means that one day on Mars is equivalent to 1.025957 Earth days.
Seasonal cycles on Mars are more similar to ours than on any other planet due to its 25.19° axial tilt. As a result, Martian days experience similar changes with the Sun rising early and setting late in the summer and vice versa in the winter.
However, seasonal changes last twice as long on Mars because the Red Planet is at a greater distance from the Sun. This results in a Martian year being twice as long as an Earth year, 686.971 Earth days or 668.5991 Martian days or Sol.
Day on Jupiter:
Given the fact that it is the largest planet in the solar system, one would expect a day on Jupiter to be long. But as it turns out, officially a day on Jupiter lasts only 9 hours 55 minutes and 30 seconds, which is less than a third of the length of an Earth day. This is due to the fact that the gas giant has a very high rotational speed of approximately 45,300 km / h. Such a high rotation speed is also one of the reasons why the planet has such violent storms.
Note the use of the word formal. Since Jupiter is not a solid body, its upper atmosphere moves at a different speed than at its equator. Basically, the rotation of Jupiter's polar atmosphere is 5 minutes faster than that of the equatorial atmosphere. Because of this, astronomers use three frames of reference.
System I is used at latitudes from 10°N to 10°S, where its rotation period is 9 hours 50 minutes and 30 seconds. System II applies at all latitudes north and south of them, where the rotation period is 9 hours 55 minutes and 40.6 seconds. System III corresponds to the rotation of the planet's magnetosphere, and this period is used by the IAU and IAG to determine Jupiter's official rotation (i.e. 9 hours 44 minutes and 30 seconds)
So, if you could theoretically stand on the clouds of a gas giant, you would see the Sun rise less than once every 10 hours at any latitude of Jupiter. And in one year on Jupiter, the Sun rises about 10,476 times.
Day on Saturn:
The situation of Saturn is very similar to Jupiter. Despite its large size, the planet has an estimated rotational speed of 35,500 km/h. One sidereal rotation of Saturn takes approximately 10 hours and 33 minutes, making one day on Saturn less than half an Earth day.
The orbital period of Saturn's rotation is equivalent to 10,759.22 Earth days (or 29.45 Earth years), and a year lasts approximately 24,491 Saturn days. However, like Jupiter, Saturn's atmosphere rotates at different rates depending on latitude, requiring astronomers to use three different frames of reference.
System I covers the equatorial zones of the South Equatorial Pole and the North Equatorial Belt, and has a period of 10 hours and 14 minutes. System II covers all other latitudes of Saturn except for the north and south poles, with a rotation period of 10 hours 38 minutes and 25.4 seconds. System III uses radio emission to measure Saturn's internal rotation rate, which resulted in a rotation period of 10 hours 39 minutes 22.4 seconds.
Using these various systems, scientists have obtained various data from Saturn over the years. For example, data acquired during the 1980s by the Voyager 1 and 2 missions indicated that a day on Saturn is 10 hours 45 minutes and 45 seconds (± 36 seconds).
In 2007 this was revised by researchers at the UCLA Department of Earth, Planetary and Space Sciences, resulting in the current estimate of 10 hours and 33 minutes. Much like Jupiter, the problem with accurate measurements is that different parts rotate at different speeds.
Day on Uranus:
As we approached Uranus, the question of how long a day lasts became more difficult. On the one hand, the planet has a sidereal rotation period of 17 hours 14 minutes and 24 seconds, which is equivalent to 0.71833 Earth days. Thus, we can say that a day on Uranus lasts almost as long as a day on Earth. This would be true were it not for the extreme axial tilt of this gas-ice giant.
With an axial tilt of 97.77°, Uranus essentially orbits the Sun on its side. This means that its north or south faces directly towards the Sun at different times of the orbital period. When it is summer at one pole, the sun will shine there continuously for 42 years. When the same pole is turned away from the Sun (that is, it is winter on Uranus), there will be darkness for 42 years.
Therefore, we can say that one day on Uranus from sunrise to sunset lasts as much as 84 years! In other words, one day on Uranus lasts as long as one year.
Also, as with other gas/ice giants, Uranus rotates faster at certain latitudes. Therefore, while the rotation of the planet at the equator, approximately 60° south latitude, is 17 hours and 14.5 minutes, the visible features of the atmosphere move much faster, making a full revolution in just 14 hours.
Day on Neptune:
Finally, we have Neptune. Here, too, the measurement of one day is somewhat more complicated. For example, Neptune's sidereal rotation period is approximately 16 hours 6 minutes and 36 seconds (equivalent to 0.6713 Earth days). But due to its gas/ice origin, the planet's poles rotate faster than the equator.
Bearing in mind that the rotation speed magnetic field planets 16.1 hours, the equatorial zone rotates approximately 18 hours. Meanwhile, the polar regions rotate for 12 hours. This differential rotation is brighter than any other planet in the solar system, resulting in strong latitudinal wind shear.
In addition, the planet's 28.32° axial tilt results in seasonal fluctuations similar to those on Earth and Mars. Neptune's long orbital period means the season lasts for 40 Earth years. But because its axial tilt is comparable to Earth's, the variation in its day length over its long year is not as extreme.
As you can see from this summary of the various planets in our solar system, the length of the day depends entirely on our frame of reference. In addition to that, the seasonal cycle varies depending on the planet in question and where the measurements are taken from on the planet.
Average long-term deceleration of the Earth's rotation
In 1995, a pair of scientists from the University of Durham (UK) and the office of the Royal Nautical Almanac carefully studied the historical information on solar and lunar eclipses since 700 BC. to 1990 from Babylon, Ancient Greece, Arab dominions, Ancient China and Europe - all these civilizations had advanced knowledge of astronomy and kept records of solar and lunar eclipses. The analysis of historical data in conjunction with modern information made it possible for the first time to draw up a graph of long-term fluctuations in the rotation of our planet. The theory was confirmed that the Earth does not rotate at the same speed. It periodically accelerates and slows down, with a long-term tendency to gradually slow down.
21 years later, the same scientists developed an updated historical graph of the Earth's rotation. It includes new historical data: approximately 25% more information on solar eclipses from Babylon, as well as corrected data on eclipses from ancient China, which corrected inaccuracies due to interpretation errors. In addition, scientists have taken a new archive of lunar eclipses from 1623 to 2015, which is compiled taking into account the most recent and accurate ephemeris of the moon, the position of the stars and the contour of the moon during eclipses. Information received from the Laboratory jet propulsion NASA.
After updating the eclipse tables based on the results of historical records, scientists calculated the difference between the time of the eclipse in relative universal time (Universal Time, UT) and absolute earth time (TT). Earth time is a modern astronomical standard developed by the International Astronomical Union to determine the time of astronomical observations made from the Earth's surface. It is designed according to the gravitational model of the solar system and does not depend on actual changes in the Earth's rotation rate.
Delta time (ΔT) in the table and graphs corresponds to the difference between TT and UT. Since mid-1955, when high-precision atomic clocks began to operate on Earth, TT has been defined as atomic clock time (TAI) plus 32.184 seconds. On the TT scale, one day is defined as 86,400 SI seconds. On the UT scale, one day corresponds to the average value of a solar day, based on the average period of the Earth's revolution around its axis.
Current fluctuations in the speed of the Earth's rotation are accurately determined from information from satellites in the Earth's orbit and the relative position of the Earth and the Moon. Laser rangefinders made it possible to accurately calculate the tidal acceleration in the Earth-Moon system (n): it is −25.82±0.03″ cy −2 .
Therefore, ΔT for a change in rotation under the influence of tidal acceleration will change over time as a parabola:
In this formula, t corresponds to Julian centuries after 1820.
It should be noted that due to large mass The moons (approximately 1/81 of the Earth's mass) the Earth-Moon system can be considered as a binary planetary system, and not as a planet with a satellite.
Lunar laser rangefinder data and tidal acceleration information is only available for the last 50 or so years, but this formula is quite applicable to historical astronomical observational data because the Earth-Moon system has not changed.
Scientists have tried to determine how the speed of the Earth's rotation in past centuries was influenced by other unknown factors, in addition to tidal acceleration.
This is how the diagram of ΔT changes looks like according to the results of all observations until 1600, more precisely, until the total solar eclipse of 1567.
Measurements after 1600 and even more so after 1700 using more advanced instruments (telescopes) significantly reduced the measurement error.
This is how the diagram of ΔT change looks like according to the results of observations from 1623 to 2015.
If we use the aforementioned parabola and represent it as a straight line, then the long-term fluctuations in the speed of the Earth's rotation form the following picture.
Scientists conclude that tidal acceleration alone cannot explain fluctuations in the speed of the Earth's rotation. Obviously, other forces influence the rotation of the planet. For example, it can be a combination of glacioisostasis (vertical movements of the earth's surface) and the gravitational interaction of the core with the Earth's mantle.
Based on the analysis of all historical data, it is possible to calculate the average long-term slowdown of the Earth's rotation, which is approximately 1.78 milliseconds per century.
The scientific work and all the initial data in tabular form was published on December 7, 2016 in the journal Proceedings of the Royal Society in the public domain for further processing by astronomers and astrologers (representatives of this pseudoscience also prefer to use real scientific data).
This concept arose in antiquity. The length of the day was not in doubt, which even found expression in the proverb: "Day and night - a day away." The time taken as the beginning of the day changed from people to people and from era to era. Now the end of the previous day and the beginning of the next is considered midnight. In ancient Egypt, the day was counted from dawn to dawn, among the ancient Jews - from evening to evening (now such an account has been preserved in the Orthodox Church).
Days on Earth
The development of science has clarified the concept of day: the time during which the planet makes a complete revolution around its axis. This movement is determined by the position of the luminaries in the sky.
In astronomy, the day is counted from the intersection of the meridian by the luminary. Such an intersection is called the upper climax, and the Greenwich meridian is traditionally taken as the starting point. What matters is the intersection of the meridian by the center of the visible solar disk (this is called the true Sun), the middle Sun (an imaginary point that, during the tropical year, makes a complete revolution around the vernal equinox point, moving evenly along the equator) and the vernal equinox point or a specific star. In the first case, they speak of true solar days, in the second, of mean solar days, and in the third, of stellar days.
The length of a sidereal day is different from the length of a solar day. The Earth not only rotates on its axis, it also rotates around the Sun. In order for the Sun to appear in the sky, the Earth has to make a little more than a complete revolution around its axis. Therefore, the duration of a solar day used in everyday life is 24 hours, and a sidereal day is 23 hours 56 minutes 4 seconds. This period of time is taken into account when solving astronomical problems.
The duration of a true solar day constantly fluctuates due to the Earth's orbit, therefore, for convenience, the calculation of time is based on the average solar day, the duration of which is 24 hours.
Day on other objects of the solar system
Even more striking phenomena concerning the length of the day can be observed on other planets and satellites. As for the latter, not only rotation around its axis and movement around the Sun is important, but also rotation around its planet and tilt of the axis. For example, on the Moon, the average solar day lasts 29 days 44 minutes 2.82 seconds on the earth, and the deviation of the true solar day from this indicator can reach 13 hours.
In addition to the Moon, Phobos, Deimos and Charon, all satellites in the solar system revolve around the giant planets. The gravity of these colossal planets slows down the rotation of satellites, so most of them have a day equal to the period of revolution around the planet. But there is one celestial body that stands out from the overall picture - Hyperion, one of the satellites of Saturn. Due to orbital resonance with another moon, Titan, its rotational speed is constantly changing. One day on Hyperion can differ from others by several tens of percent!
Among the planets, Mars is closest to the Earth in terms of the length of the day: the Martian day lasts 24 hours 39 minutes 35.244 seconds.
"Record holders" for the duration of the day can be considered Venus and Jupiter. On Venus, the day is the longest - 116 Earth days, and on Jupiter - the shortest, a little less than 10 hours. However, in relation to Jupiter and other gas giants, the length of the day is only spoken of as an average. The substance that makes up gas ball, rotates at different speeds on different geographical latitudes. For example, the exact duration of a day at Jupiter's equator is 9 hours 50 minutes 30 seconds, and at the poles it is one second less.