What does Mars mean?

Mars is one of the eight planets in the solar system and the fourth planet in the solar system from the inside out. It is a terrestrial planet, with a diameter of about 53% of the Earth's and a mass of 1 1% of the Earth's. Due to the axial tilt, the rotation period is similar to that of the earth, and one circle is about twice that of the earth. The orange appearance is the surface hematite (iron oxide). In China's ancient books, Mars was called "the twinkling star", while in ancient western countries (ancient Rome) it was called "the star in the myth of Mars".

Mars is basically a desert planet, its surface is covered with sand dunes and gravel, and there is no stable liquid water body (2065438+September 28th, 2005, NASA announced that there is a small amount of water on Mars. According to Agence France-Presse reported on July 25th, 20 18, researchers from the European Space Agency (ESA) said that the first liquid groundwater lake was discovered on Mars. The atmosphere dominated by carbon dioxide is thin and cold, and dust is suspended in it, and dust storms often occur every year. The polar caps composed of water ice and dry ice at the poles of Mars will fluctuate with the seasons.

Compared with the earth, the geological activities of Mars are relatively inactive. Most of the surface landforms were formed in ancient times, with dense craters, volcanoes and canyons, including Mount Olympus, the highest peak in the solar system, and Mariner Canyon, the largest canyon. Another unique topographical feature is the obvious difference between the northern and southern hemispheres: the southern part is an ancient highland covered with craters, while the northern part is a younger plain.

The average distance between Mars and the sun is 1.52AU (astronomical unit), and period of revolution has 687 Earth days, 1.88 Earth years (hereinafter referred to as years), or 668.6 Mars days. The average Martian day is 24 hours, 39 minutes and 35.244 seconds, that is,1.05,438+0 Earth days.

Mars has an off-axis inclination of 25. 19 degrees, which is similar to that of the earth, so there are four seasons, but the length of the four seasons is about twice. Because the eccentricity of Mars orbit is about 0.093 (the earth is only 0.0 17), the length of each season is inconsistent, and because the apohelion is close to the summer solstice in the northern hemisphere, spring and summer in the northern hemisphere are about 40 days longer than autumn and winter. June 26, 2009 is the vernal equinox in the northern hemisphere, and 438+00 is the summer solstice on May 65, 2065, with spring in the northern hemisphere.

The orbit of Mars, like that of the Earth, is constantly changing under the influence of other celestial bodies in the solar system. There are two cycles of track eccentricity, which are 96,000 years and 2. 1 10,000 years respectively, and the range is 0.002-0. 12. On the other hand, the years of the Earth are100000 and 4,654.38+03000, ranging from 0.005 to 0.058 (see Milankovic cycle), and the shortest distance from Mars to the Earth is gradually decreasing.

As for the tilt angle of the axis, Mars is 25. 19 degrees, but it can change from 13 degrees to 40 degrees in more than10 million years, unlike the stability of the earth, which is between 22. 1 and 24.5 degrees, because Mars does not have a huge satellite like the moon to maintain its rotation axis. Because there is no tidal action of large satellites, the rotation period of Mars does not change much, unlike the earth, which will slowly lengthen. Therefore, the similarity of the rotation periods of the two planets is only a temporary phenomenon.

Baidu Encyclopedia-Mars