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Numerous attempts [3] [4] [5] have been made over the years to determine an absolute Martian chronology (timeline) by comparing estimated impact cratering rates for Mars to those on the Moon. If the rate of impact crater formation on Mars by crater size per unit area over geologic time (the production rate or flux) is known with precision, then ...
It is slightly shorter than the sidereal year due to the precession of Mars' rotational axis. 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 2023 study shows evidence, based on the orbital inclination of Deimos (a small moon of Mars), that Mars may once have had a ring system 3.5 billion years to 4 billion years ago. [32] This ring system may have been formed from a moon, 20 times more massive than Phobos , orbiting Mars billions of years ago; and Phobos would be a remnant of that ...
The absolute age of the Noachian period is uncertain but probably corresponds to the lunar Pre-Nectarian to Early Imbrian periods [2] of 4100 to 3700 million years ago, during the interval known as the Late Heavy Bombardment. [3] Many of the large impact basins on the Moon and Mars formed at this time.
An epoch is a subdivision of a period; the two terms are not synonymous in formal stratigraphy. The age of the Early Hepserian/Late Hesperian boundary is uncertain, ranging from 3600 to 3200 million years ago based on crater counts. [5] The average of the range is shown in the timeline below.
The lower boundary of the Pre-Noachian period on Mars is characterized by the emergence of significant geological activity and the initial shaping of the planet's surface during its early history. This boundary is defined by the presence of ancient cratered terrains, volcanic constructs, and impact ejecta deposits dating back to the earliest ...
Extra-close oppositions of Mars happen every 15 to 17 years, when we pass between Mars and the Sun around the time of its perihelion (closest point to the Sun in orbit). The minimum distance between Earth and Mars has been declining over the years, and in 2003 the minimum distance was 55.76 million km, nearer than any such encounter in almost ...
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 .