What is Mars like?

Mars (Latin: Mars) is the fourth closest planet to the sun, the second asteroid in the solar system after Mercury, and one of the four terrestrial planets in the solar system.

In the west, Mars is called Mars myth and the god of war in Roman mythology, so in English, Mars means Roman god of war and is usually called "red planet". In ancient Chinese, it was called "flicker" because it was as bright as fire, and its position and brightness were often unpredictable.

Mars is the second smallest planet among the eight planets in the solar system, and its mass and volume are only slightly larger than that of Mercury. The diameter of Mars is about half that of the Earth. The rotation period from the tilt of the axis is equivalent to that of the Earth, but the period of revolution around the sun is twice that of the Earth. On the earth, Mars is visible to the naked eye, and its brightness can reach -2.9 1, which is only darker than Venus, the moon and the sun, but it is darker than Jupiter most of the time. Mars is 54 million kilometers away from the earth (up to 400 million kilometers at the farthest, and it takes about 7 months for the probe to fly to Mars).

The atmosphere of Mars is mainly carbon dioxide, which is thin and cold. Its surface features are reminiscent of craters, valleys, deserts and polar ice sheets on the moon. In English, it is usually called the red planet. It is because Mars is orange-red visually, and because of the iron oxide widely distributed on the earth's surface, Mars has a red appearance and is unique among celestial bodies visible to the naked eye.

The surface of Mars is covered with sand dunes and gravel, and there is no stable liquid water. The southern hemisphere of Mars is an ancient highland covered with craters, while the northern hemisphere is a younger plain.

Unmanned spacecraft have explored Mars. 1964165438+1On October 28th, Mariner 4 launched by NASA was the first spacecraft to visit Mars, and it came closest to the planet on July 1965. The Soviet Mars-3 spacecraft made a soft landing in19712, but lost contact within a few seconds after landing. The first Mars express of the European Space Agency visited Mars on February 25th, 2003 and reached the orbit. 20 14 On September 24th, the Indian Space Research Organization became the fourth space agency to visit Mars, when its interplanetary mission, the Mars orbiter mission, reached orbit.

Mars has two natural satellites: Phobos and Phobos, which are irregular in shape and may be captured asteroids.

At present, there are four probes in the orbit of Mars, namely, the Mars Odyssey, the Mars Express and the Mars Reconnaissance Orbiter, and the MAVEN Orbiter which arrived on September 22nd, 20th14th. There are also many rovers and landers on the surface, including a rover: Curiosity, fixed landing probe Insight, and rovers, Spirit, Phoenix and Opportunity that have completed their missions. According to observational evidence, Mars may have covered a large area of water before. A similar phenomenon of groundwater gushing has been observed in recent ten years.

Mars global surveyors have observed that the Antarctic crown has partially retreated. The radar data of Mars Express and Mars Reconnaissance Orbiter show that there are a lot of water ice under the polar and mid-latitude surface.

On July 3, 20081day, Phoenix confirmed the existence of water ice directly below the topsoil. On September 26th, 20 13, Curiosity, a Mars probe, discovered that the soil of Mars is rich in water, which is about 1.5-3 weight percentage, indicating that Mars has enough water resources for future immigrants. September 20 15 confirmed the existence of intermittent liquid water (liquid salt water) on Mars. On July 25th, 20 18, the Italian Space Agency announced the discovery of an ice lake with a diameter of 20km under the ice cover of Mars. This is the first large-scale liquid water body detected by space scientists on Mars.