What color is Mars?

It is red,

Mars

Mars is the fourth farthest planet from the sun and the seventh largest planet in the solar system:

Mars Basic parameters:

Orbital semi-major diameter: 227.94 million kilometers (1.52 astronomical units)

Revolution period: 686.98 days

Average orbital speed: 24.13 kilometers/ per second

Orbital eccentricity: 0.093

Orbital inclination: 1.8 degrees

Planetary equatorial radius: 3398 kilometers

Mass (Earth Mass = 1): 0.1074

Density: 3.94 g/cm3

Rotation period: 1.026 days

Number of satellites: 2

Orbit: 227,940,000 kilometers (1.52 astronomical units) from the sun

Mars (Greek: Ares) is known as the god of war. This may be due to its bright red color; Mars is sometimes called the "red planet." (Interesting note: Before the Greeks, the ancient Romans worshiped Mars as the god of farming. However, the aggressive and expansionist Greeks used Mars as a symbol of war) and the name "March" is also derived from Mars.

Mars has been known to humans since prehistoric times. Because it is considered the best place for humans to live in the solar system (other than Earth), it is beloved by science fiction writers. But it is a pity that the famous "canal" "seen" by Lowell and others are just as fictional as the Barsoomian princesses.

The first exploration of Mars was carried out by the Mariner 4 spacecraft in 1965. Several more attempts were made, including two Viking aircraft in 1976 (pictured left). After that, after a gap of 20 years, on July 4th, 1997, the Mars Pathfinder finally successfully landed on Mars (pictured on the right).

The orbit of Mars is significantly elliptical. Therefore, in a place receiving sunlight, the temperature difference between perihelion and aphelion is nearly 30 degrees Celsius. This has a huge impact on the climate of Mars. The average temperature on Mars is approximately 218K (-55°C, -67°F), but ranges from 140K (-133°C, -207°F) in winter to nearly 300K (27°C, 80°F) during the day in summer. ) span. Although Mars is much smaller than Earth, its surface area is equivalent to the land area on Earth's surface.

Other than Earth, Mars is the solid surface planet with the most variety of interesting terrain. There are some spectacular terrains:

- Olympus Mountains: At 24 kilometers (78,000 feet) above the surface, it is the largest mountain range in the solar system. Its base is more than 500 kilometers in diameter and is surrounded by a cliff 6 kilometers (20,000 feet) high (right);

-Tharsis: A huge bulge on the surface of Mars, about 4,000 kilometers wide and 10 kilometers high;

- Valles Marineris: a group of canyons 2 to 7 kilometers deep and 4,000 kilometers long (picture below title);

- Hellas Planitia: An impact crater in the Southern Hemisphere with a depth of more than 6,000 meters and a diameter of 2,000 kilometers.

There are many ancient craters on the surface of Mars. But there are also many recently formed valleys, ridges, hills and plains.

In the southern hemisphere of Mars, there is a curved ring-shaped highland similar to that on the moon (pictured left). In contrast, its northern hemisphere is mostly composed of recently formed low, flat plains. The formation of these plains is complex. Huge altitude changes of several kilometers occur on the north-south border. The reasons for the huge difference in terrain between the north and the south and the drastic changes in height in the border area are still unknown (some people speculate that this is due to the huge force generated at the moment when the outer layer of Mars increases). Recently, some scientists have begun to wonder whether those steep mountains are where they once were. This doubt will be solved by the "Mars Global Surveyor".

The internal conditions of Mars can only be inferred based on its surface conditions and a large amount of related data. It is generally believed that its core is composed of high-density material with a radius of 1,700 kilometers; it is surrounded by a layer of lava, which is thicker than the Earth's mantle; and the outermost layer is a thin outer shell.

Mars' low density relative to other solid planets suggests that the iron (magnesium and iron sulfide) in the Martian core may contain more sulfur.

Like Mercury and the Moon, Mars lacks active plate tectonics; there is no sign that Mars has experienced the kind of crustal translational activity that would create such folded mountain systems as Earth's. Because there is no lateral movement, the hot zone under the earth's crust is in a stationary state relative to the ground. This, coupled with the slight gravitational pull of the ground, created the Tharis bulge and huge volcanoes. However, no signs of recent activity have been found on the volcano. Although Mars may have experienced a lot of volcanic activity, it appears to have never had any plate tectonics.

There have been floods on Mars, and there are also some small channels on the ground (pictured on the right), which is very clear evidence of erosion in many places. In the past, clean water existed on the surface of Mars, and there may even have been large lakes and oceans. But these things appear to have only been around for a short time, and are estimated to be around four billion years old. (Valles Marneris was not formed by the passage of water. It was created by the stretching and impact of the shell, along with the Tharsis bulge).

In its early days, Mars was very similar to Earth. Like Earth, nearly all carbon dioxide on Mars is converted into carbon-containing rocks. But without the movement of Earth's plates, Mars cannot recycle carbon dioxide into its atmosphere to create a meaningful greenhouse effect. Therefore, even if you bring it to the same distance as Earth from the sun, the temperature on the surface of Mars is still much colder than that on Earth.

The thin atmosphere of Mars is mainly composed of remaining carbon dioxide (95.3%) plus nitrogen (2.7%), argon (1.6%) and trace amounts of oxygen (0.15%). Composed of water vapor (0.03%). The average atmospheric pressure on the surface of Mars is only about 7 millibars (less than 1% that on Earth), but it varies with altitude, reaching as high as 9 millibars in the deepest basins and at the top of Olympus Mons But it's only 1 millibar. But it's also strong enough to support the hurricanes and giant storms that occasionally sweep across the planet for entire months. Although Mars' thin atmosphere can also create a greenhouse effect, it can only increase the temperature of its surface by 5K, which is much less than what we know about Venus and Earth.

The poles of Mars are permanently covered in solid carbon dioxide (dry ice). The structure of this ice cap is stacked, consisting of layers of ice and changing layers of carbon dioxide. During northern summers, carbon dioxide completely sublimates, leaving a remaining layer of ice and water. Because the carbon dioxide in the south never completely disappeared, we don't know whether there was also a layer of ice water beneath the ice in the south (left). The cause of this phenomenon is not known, but it may be caused by changes in the climate caused by long-term changes in the angle between the equatorial plane of Mars and its orbit. There may also be water deeper beneath the surface of Mars. This change in polar cover due to seasonal changes changes Mars' air pressure by about 25% (measured by Viking).

But recent observations through the Hubble Telescope have shown that the environment during the Viking survey was not typical. The Martian atmosphere now appears to be cooler and drier than what the Viking probes detected (details from STScI).

The Vikings tried experiments to determine whether there was life on Mars, but the results were negative. But optimists point out that only two small samples are qualified, and they don't come from the best places. Future Mars explorers will continue more experiments.

A small meteorite (SNC meteorite) is thought to come from Mars.

On August 6, 1996, David McKay and others announced that organic matter was discovered for the first time in a Martian meteorite. The author even said that this composition, plus some other minerals obtained from meteorites, could be evidence of ancient microorganisms on Mars. (Picture on the left?)

Such a surprising conclusion, but it does not establish the conclusion that aliens exist. Since David Zhu developed his opinion, a number of studies by opponents have also been published. But any conclusion should be "reasonable and well-founded." There is still much to do before a conclusion can be announced with any certainty.

There is a large area of ??weak gravity in the tropical regions of Mars. This was an unexpected discovery made by the Mars Global Surveyor as it entered Mars orbit. They may have been left behind when earlier shells disappeared. This may be very useful for studying the internal structure of Mars, past air pressure conditions, and even the possibility of ancient life.

In the night sky, Mars is easily visible with the naked eye. Because it is very close to the Earth, it appears very bright. Mike Harvey's planet-finding chart shows the location of Mars and other planets in the sky. More and more details, and better and better diagrams will be discovered and completed by astronomical programs like Starlight.

Satellites of Mars

Mars has two small near-ground satellites.

Satellite distance (kilometer) Radius (kilometer) Mass (kilogram) Discoverer Discovery date

Phobos 9000 11 1.08e16 Hall 1877

Fire Moon 23000 6 1.80e15 Hall 1877