Mars (planet)

Article

August 13, 2022

Mars (symbol: ) is the fourth planet from the sun in our solar system and is named after the Roman god of war Mars. The planet is often described as the "red planet" because of its rust-red appearance, caused by iron(III) oxide on the surface. Mars is a rocky planet with a thin atmosphere. The surface features are reminiscent of both the impact craters on the moon and the volcanoes, valleys, deserts and polar ice caps on Earth. The rotation period and seasonal cycles on Mars are also similar to Earth since it is the tilt of the axis that leads to the seasons. Olympus Mons is the highest known mountain in the solar system, and Valles Marineris is the largest valley system. The flat Borealis Basin in the Northern Hemisphere covers approx. 40% of the planet and may originate from a giant impact. Before Mariner 4 carried out the first flyby in 1965, it was speculated whether there was liquid water on the surface. Regular variations in light and dark spots, especially at the polar latitudes, could be interpreted as oceans and continents. Long, dark striations were interpreted as channels of liquid water. These straight line formations were later explained as optical illusions, but geological evidence collected by unmanned missions suggests that Mars once had large areas covered by water on its surface. In 2005, radar data revealed large amounts of ice at the poles and milder latitudes. The Mars probe Spirit collected samples of chemical compounds containing water molecules in March 2007. The Phoenix lander collected samples of ice in shallow soil on July 31, 2008. On September 28, 2015, NASA announced that they had found evidence of flowing salty water beneath the surface of Mars. Mars has two small moons, Phobos and Deimos, which are irregularly shaped. These may be captured asteroids similar to the Trojan asteroid 5261 Eureka. Three functional and unmanned spacecraft orbit the planet: Mars Odyssey, Mars Express and Mars Reconnaissance Orbiter. On the surface are the Mars Exploration Rover Opportunity and its decommissioned twin Spirit, the Curiosity rover, along with a number of other inactive landers and rovers, both successful and failed. The Phoenix lander completed its mission on the surface in 2008. Observations by NASA's now-defunct Mars Global Surveyor prove that parts of the Southern Pole have retreated. Observations by NASA's Mars Reconnaissance Orbiter have revealed possible flowing water during the hottest months on Mars. In 2013, the rover Curiosity revealed that the soil contains 1.5–3% water, or 33 liters per m³. Mars can easily be seen from Earth with the naked eye. Its apparent magnitude reaches −3.0, which is beaten only by Venus, Jupiter, the Moon and the Sun. The ancient planetary symbol is the same as the symbol for iron (♂), a stylized version of the god Mars with shield and spear.

Physical Characteristics

Mars is about half the diameter of Earth, and with about 15% of Earth's volume and 11% of its mass, it has a lower density than Earth. The surface area is slightly less than the total area of ​​the Earth's mainland. Although Mars is larger and more massive than Mercury, Mercury has a higher density. The two planets have roughly equal gravitational pull at the surface – less than 1% stronger on Mars. Compared to Earth and the Moon, Mars is about average in size, mass and surface gravity – the Moon is about half the diameter of Mars while the Earth is twice that; the earth is about nine times as massive as mars while the moon is about one ninth as massive. The red-orange appearance of the Martian surface is caused by iron(III) oxide, best known as hematite or rust.

Internal structure

Like Earth, Mars has undergone planetary differentiation, where a dense, metallic core has been surrounded by less dense materials. Models show a partially liquid core of iron sulphides of about 1,794±65 km in radius, consisting primarily of