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| | Spirit, NASA's robotic rover which is not on the surface of Mars, has extended its mechanical arms for the first time. It is now taking extraordinarily close photos of the rush colored soil of Mars. Mars is 300 million miles from Earth.
Red Planet: Mars
In our solar system, planet Mars is located at fourth position from the Sun and according to size it is the seventh largest planet. Planet Mars received its name from the Roman god of war, corresponding to the one called as Ares in Greek mythology. Mars is sometimes also referred as the ‘Red Planet’ because of its reddish surface, which can be attributed to iron oxide.
General Information:
Mars belongs to the family of terrestrial planets with an atmosphere that has very low-density. Features of the topography of Mars surface can be compared with the lunar craters and volcanoes, valleys, deserts and polar ice caps like the ones seen on Earth. Extinct volcano Mount Olympus on Mars is the highest mountain in our solar system, and Mariner Valley on the planet is the largest canyon. In addition, three articles were published in the journal Nature in 2008 that put forward the evidence that Mars has an impact crater on its northern hemisphere that is the largest known in the solar system. Its length is 10,600 km and width is 8500 km, and it is roughly four times larger than the earlier known largest impact crater, also located on Mars near its south pole. In addition to the similarity of its surface topography, rotation intervals and changing of seasons on Mars are also similar to Earth, but its climate is much colder and drier than on Earth.
Until the first fly-by mission to Mars ‘Mariner 4’ in 1965, many researchers were of the view that its surface is water in liquid state. This opinion was based on the observations of periodic variations in light and dark areas, particularly in the polar latitudes, which looked like continents and oceans. Dark fossae on Martian surface were interpreted by some experts as irrigation canals for liquid water. Later it was discovered that it was just an optical illusion and there were no such depressions.
Because of low-pressure on the surface of Mars, water can not exist in liquid state there, but it is quite possible that conditions were different in the past, and therefore the existence of elementary life on the planet can not be ruled out. On July 31, 2008 NASA’s Phoenix lander discovered water in the form of ice on Mars.
Currently (as of February 2009), there are three operational spacecraft engaged in the research of Mars: ‘Mars Odyssey’, ‘Mars Express’ and ‘Mars Reconnaissance Orbiter’, and the number is more than on any other planet except Earth. Mars at the moment also has two exploring rovers viz. Spirit and Opportunity. Mars also has on its surface many inactive landers and rovers that have already completed their mission. Geological data, collected by all these missions, suggest that a large part of Martian surface was covered with water in the past. Studies over the past decade have also revealed geyser like activity at some places on the surface of Mars. Based on the observations from NASA’s ‘Mars Global Surveyor’ some parts on the southern polar cap of Mars have been gradually receding.
Mars has two natural satellites, Phobos and Deimos (in Greek they mean ‘panic/fear’ and ‘terror/dread’ - the names of two sons of Ares that accompanied him to battle), which are relatively small and irregular in shape. These may be the asteroids, captured by the gravitational field of Mars, and similar to Asteroid 5261 Eureka from the Trojan group.
Mars can be seen from Earth with the naked eye. Its apparent magnitude is about 2.91 m (at closest approach to Earth), and its brightness is exceeded only by Jupiter, Venus, Moon and Sun.
Minimum distance of Mars from Earth is 55.75 million miles (when Earth comes exactly between the Sun and Mars), and the maximum is about 401 million km (when the Sun is exactly between Earth and Mars). Average distance from Mars to Sun is 228 million km (1.52 AU), its orbital period around the sun equals 687 Earth days. The orbit of Mars has quite noticeable eccentricity (0.0934), that is why its distance from the Sun varies from 206.6 to 249.2 million km. Inclination of Martian orbit is equal to 1.85 °.
Physical Characteristics:
Mars is almost half the size of Earth and its equatorial radius is 3396.9 km (53.2% that of the Earth). The surface area of Mars is approximately equal to the land area on Earth. Sufficiently fast rotation of the planet has led to significant flattening which is evident from the fact that polar radius of Mars is about 21 km less than the equatorial one. Mass of the planet is 6,418 × 1023 kg (11% of Earth’s mass). Gravitational acceleration at its equator is equal to 3.711 m / s² (0.378 that of the Earth), orbital velocity is 3.6 km / sec and its escape velocity is 5.027 km / sec.
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