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Around 200 BCE Eratosthenes determines that the radius of the Earth is roughly 6,400 km. [43] Circa 150 BCE Hipparchus uses parallax to determine that the distance to the Moon is roughly 380,000 km. [44] The work of Hipparchus about the Earth-Moon system was so accurate that he could forecast solar and lunar eclipses for the next six centuries.
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The precession cycle is 93,000 Martian years (175,000 Earth years), much longer than on Earth. Its length in tropical years can be computed by dividing the difference between the sidereal year and tropical year by the length of the tropical year.
A Martian year is equal to 1.8809 Earth years, or 1 year, 320 days, and 18.2 hours. [2] The gravitational potential difference and thus the delta-v needed to transfer between Mars and Earth is the second lowest for Earth. [186] [187] The axial tilt of Mars is 25.19° relative to its orbital plane, which is similar to the axial tilt of Earth. [2]
A collection of Martian rocks could reveal details about potential past life on the Red Planet – but first NASA has to get them back to Earth.. For years, the U.S. space agency's Perseverance ...
The smallest of these, Kepler-42d, is about the size of Mars with a radius of only 0.57 times that of Earth. Not long ago, in Dec. of 2011, the Kepler team announced the discovery of Kepler-20e and Kepler-20f -- the first Earth-size planets ever found outside the solar system.
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The basic time periods from which the calendar is constructed are the Martian solar day (sometimes called a sol) and the Martian vernal equinox year.The sol is 39 minutes 35.244 seconds longer than the Terrestrial solar day, and the Martian vernal equinox year is 668.5907 sols in length (which corresponds to 686.9711 days on Earth).