Understand the benefits of Mars.

Mars is one of the eight planets in the solar system. It is 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. Because of its axial tilt, its rotation period is similar to that of the earth, and its revolution time is about twice as long as that of the earth. In the west, it is called "Mars myth". The orange-red surface is hematite (iron oxide) on the ground.

Mars is basically a desert planet with sand dunes and gravel on its surface and no stable liquid water body. 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, geological activities are relatively inactive, and most of the surface landforms were formed in an active period 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.

Mars has two natural satellites: Phobos and Phobos, which are irregular in shape and may be captured asteroids. On earth, Mars is visible to the naked eye, with the highest brightness reaching -2.9. Among the eight planets, it is darker than Jupiter and Venus.

20 13, 13 The detection data released in February show that there are dried-up ancient lakes or evidence of life on Mars. [ 1]

In 20 14, scientists from the university of Hawaii found that "Martian blueberries" were the remnants of small meteorites, which could not prove the existence of flowing water on ancient Mars. [2]

Mars is the fourth planet in the solar system from the inside out.

Mars is about half the diameter of the earth, with a volume of 15% and a mass of 1 1%. Its surface area is equivalent to the land area of the earth, but its density is much less than that of the other three terrestrial planets (Earth, Venus and Mercury). In terms of radius, mass and surface gravity, Mars is about halfway between the earth and the moon: its diameter is about twice that of the moon and half that of the earth; Its mass is about 9 times that of the moon and19 of the earth, and its surface gravity is about 2.5 times that of the moon and 2/5 of that of the earth.

Mars is the fourth planet in the solar system from the inside out, belonging to the earth-like planet. Its diameter is about half that of the earth, and it takes twice as long to make a revolution tilted from the axis with a similar rotation period. The West calls it Mars Mythology Star, God of War and China call it Fluorescent Star, because it is as bright as fire, and its position and brightness often change. Its orange-red appearance is because the surface is covered with hematite (iron oxide), and the prefix areo- is Mars in English. Mars is considered to be the most likely planet in the solar system to have extraterrestrial life.

Mars is basically a desert planet, with sand dunes and gravel all over the surface and no stable liquid water body. The atmosphere dominated by carbon dioxide is thin and cold, and dust is suspended in it. Every year, sandstorms often occur. Compared with the earth, the geological activity is inactive, and most of the surface landforms formed dense craters, volcanoes and canyons in ancient times. Including Olympus Mons, the highest mountain 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. Both poles of Mars have polar caps mainly composed of water and ice, and the dry ice covered on them will fluctuate with the seasons.

The distance from Mars to the Earth

The shortest distance is about 55 million kilometers and the longest distance is over 400 million kilometers. Close contact between them occurs about once every 15 years. In 1988, the distance between Mars and the earth once reached about 58.8 million kilometers, but in 20 18, the distance between them will reach 57.6 million kilometers. But on August 27th, 2003, the distance between Mars and the Earth was only about 55.76 million kilometers, the latest time in 60,000 years.

However, according to astronomers' calculations, during the 800 years from 1600 to 2400, the distance between Mars and the Earth can only rank third. According to the calculation results, by September 2, 2366, the distance between them was about 557 10000 km. By August 28, 2287, the two will be closer, with a distance of about 55.69 million kilometers.

Generally speaking, the year when Mars is close to the Earth is the best time to land on Mars and observe it on the ground.

(The picture shows Mars and its natural satellites Phobos and Deimos observed in the virtual planetarium stellarium. )

Mars is called the god of war in the west, perhaps because of its bright red color, so Mars is sometimes called the "red planet". (Before the Greeks, the ancient Egyptians once worshipped Mars as a god of agriculture. Later, the ancient Greeks regarded Mars as Ares, while the ancient Romans inherited the Greek myth and called it "Mars Myth". In Norse mythology, Mars is Tyr, the god of war. And the name of March also comes from Mars. )

Mars was called "fluorescent star" in ancient China, because it is red and fluorescent like fire, which symbolizes fire in the five elements, and its brightness often changes; And in air movement, sometimes from west to east, sometimes from east to west, the situation is complicated and chaotic, so China called it "Yingying" in ancient times, which means "Yingying firelight, leaving chaos". [3]

The orbit of Mars is elliptical. Therefore, where the sun shines, the temperature difference between perihelion and aphelion is close to 160 degrees Celsius. This has a great influence on the climate of Mars. The average temperature on Mars is about 2 18K (Kelvin, degree-day, that is, from absolute zero -273. 15℃(-55℃, -67℉), but it is 140k(- 133℃) away from winter. Although Mars is much smaller than the earth, its surface area is equivalent to the land area of the earth's surface.

atmosphere

The atmospheric density of Mars is only about 1% of that of the Earth, which is very dry, with low temperature and average surface.

When the temperature is MINUS 55℃, water and carbon dioxide are easy to freeze. In the early days of Mars, it was very similar to Earth. Like the earth, almost all the carbon dioxide on Mars has been converted into carbonaceous rocks. However, due to the lack of plate movement of the earth, Mars can't recycle carbon dioxide into its atmosphere again, so it can't produce significant greenhouse effect. Therefore, even if it is pulled to the same distance from the sun as the earth, the temperature on the surface of Mars is still much colder than the earth.

The thin atmosphere of Mars is mainly composed of carbon dioxide (95.3%), nitrogen (2.7%), argon (1.6%), trace oxygen (0. 15%) and water vapor (0.03%). The average atmospheric pressure on the surface of Mars is only about 7 mbar (lower than 65,438+0% on Earth), but it varies with height, reaching 9 mbar in the deepest part of the basin and only 65,438+0 mbar at the top of Olympus. But it is enough to support hurricanes and big storms that occasionally sweep the whole earth. Although the thin atmosphere of Mars will also cause greenhouse effect, those that can only raise the surface temperature by 5℃ are much less than Venus and the Earth as we know them.

The poles of Mars are permanently covered with solid carbon dioxide (dry ice). The structure of this ice sheet is layered, which is formed by the alternating overlapping of ice layers and the change of carbon dioxide layers. In the summer in the north, carbon dioxide is completely sublimated, and the rest is the ice water layer. Since the carbon dioxide in the south has never completely disappeared, we can't know whether there is ice under the ice in the south (left). The reason for this phenomenon is unknown, but it may be that the long-term change of the angle between the equatorial plane of Mars and its orbit leads to climate change. Maybe there is water deeper under the surface of Mars. This change in polar cover caused by seasonal changes has changed the pressure on Mars by about 25%. (Viking survey). However, the observation by Hubble telescope shows that the environment of Viking at that time was not typical. The atmosphere of Mars seems colder and drier than that detected by Viking.

The existence of water

Under the low pressure of Mars, water can't exist in liquid state, but only exists briefly at low altitude. There is a lot of ice, for example, the polar ice cap contains a lot of ice. [4] In March 2007, NASA claimed that if all the ice in the Antarctic crown melted, it might cover the whole earth.

1 1 m deep. In addition, the underground water frozen soil can extend from the polar regions to the latitude of about 60.