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It is approximately 24 hours, 39 minutes, 35 seconds long. A Martian year is approximately 668.6 sols, equivalent to approximately 687 Earth days [ 1 ] or 1.88 Earth years. The sol was adopted in 1976 during the Viking Lander missions and is a measure of time mainly used by NASA when, for example, scheduling the use of a Mars rover .
The local mean solar time is also affected by the rover motion; at 4.6°S, this is about 1 second of time difference for every 246 meters of displacement along the east–west direction. The date is kept using a mission clock sol count with the landing occurring on Sol 0, corresponding to MSD 49269 (mission time zone); the landing occurred ...
This has been translated either as 4 080 000 stadia (1903 translation by Edwin Hamilton Gifford), or as 804 000 000 stadia (edition of Édouard des Places, dated 1974–1991). Using the Greek stadium of 185 to 190 metres, [ 32 ] [ 33 ] the former translation comes to 754 800 km to 775 200 km , which is far too low, whereas the second ...
Solar radius is a unit of distance used to express the size of stars in astronomy relative to the Sun.The solar radius is usually defined as the radius to the layer in the Sun's photosphere where the optical depth equals 2/3: [1]
The astronomical unit of length is now defined as exactly 149 597 870 700 meters. [4] It is approximately equal to the mean Earth–Sun distance. It was formerly defined as that length for which the Gaussian gravitational constant (k) takes the value 0.017 202 098 95 when the units of measurement are the astronomical units of length, mass and ...
For solid objects, such as rocky planets and asteroids, the rotation period is a single value.For gaseous or fluid bodies, such as stars and giant planets, the period of rotation varies from the object's equator to its pole due to a phenomenon called differential rotation.
The Sun is 1.4 million kilometers (4.643 light-seconds) wide, about 109 times wider than Earth, or four times the Lunar distance, and contains 99.86% of all Solar System mass. The Sun is a G-type main-sequence star that makes up about 99.86% of the mass of the Solar System. [ 26 ]
The largest unit for expressing distances across space at that time was the astronomical unit, equal to the radius of the Earth's orbit at 150 million kilometres (93 million miles). In those terms, trigonometric calculations based on 61 Cygni's parallax of 0.314 arcseconds, showed the distance to the star to be 660 000 astronomical units (9.9 ...