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Overview
Mars is the fourth planet from the sun. Befitting the red planet's bloody color, the Romans named it after their god of war. The Romans copied the ancient Greeks, who also named the planet after their god of war, Ares. Other civilizations also typically gave the planet names based on its color — for example, the Egyptians named it "Her Desher," meaning "the red one," while ancient Chinese astronomers dubbed it "the fire star."
Regolith
The bright rust color Mars is known for is due to iron-rich minerals in its regolith — the loose dust and rock covering its surface. The soil of Earth is a kind of regolith, albeit one loaded with organic content. According to NASA, the iron minerals oxidize, or rust, causing the soil to look red.
Geology
The cold, thin atmosphere means liquid water currently cannot exist on the Martian surface for any length of time. This means that although this desert planet is just half the diameter of Earth, it has the same amount of dry land.
The red planet is home to both the highest mountain and the deepest, longest valley in the solar system. Olympus Mons is roughly 17 miles (27 kilometers) high, about three times as tall as Mount Everest, while the Valles Marineris system of valleys — named after the Mariner 9 probe that discovered it in 1971 — can go as deep as 6 miles (10 km) and runs east-west for roughly 2,500 miles (4,000 km), about one-fifth of the distance around Mars and close to the width of Australia or the distance from Philadelphia to San Diego.
Mars has the largest volcanoes in the solar system, including Olympus Mons, which is about 370 miles (600 km) in diameter, wide enough to cover the entire state of New Mexico. It is a shield volcano, with slopes that rise gradually like those of Hawaiian volcanoes, and was created by eruptions of lavas that flowed for long distances before solidifying. Mars also has many other kinds of volcanic landforms, from small, steep-sided cones to enormous plains coated in hardened lava. Some minor eruptions might still occur on the planet.
The red planet is home to both the highest mountain and the deepest, longest valley in the solar system. Olympus Mons is roughly 17 miles (27 kilometers) high, about three times as tall as Mount Everest, while the Valles Marineris system of valleys — named after the Mariner 9 probe that discovered it in 1971 — can go as deep as 6 miles (10 km) and runs east-west for roughly 2,500 miles (4,000 km), about one-fifth of the distance around Mars and close to the width of Australia or the distance from Philadelphia to San Diego.
Mars has the largest volcanoes in the solar system, including Olympus Mons, which is about 370 miles (600 km) in diameter, wide enough to cover the entire state of New Mexico. It is a shield volcano, with slopes that rise gradually like those of Hawaiian volcanoes, and was created by eruptions of lavas that flowed for long distances before solidifying. Mars also has many other kinds of volcanic landforms, from small, steep-sided cones to enormous plains coated in hardened lava. Some minor eruptions might still occur on the planet.
Polar caps
Vast deposits of what appear to be finely layered stacks of water ice and dust extend from the poles to latitudes of about 80 degrees in both hemispheres. These were probably deposited by the atmosphere over long spans of time. On top of much of these layered deposits in both hemispheres are caps of water ice that remain frozen all year round. Additional seasonal caps of frost appear in the wintertime. These are made of solid carbon dioxide, also known as "dry ice," which has condensed from carbon dioxide gas in the atmosphere, and in the deepest part of the winter, this frost can extend from the poles to latitudes as low as 45 degrees, or halfway to the equator. The dry ice layer appears to have a fluffy texture, like freshly fallen snow, according to the report in the Journal of Geophysical Research-Planets.
Climate
Mars is much colder than Earth, in large part due to its greater distance from the sun. The average temperature is about minus 80 degrees Fahrenheit (minus 60 ` Celsius), although they can vary from minus 195 F (minus 125 C) near the poles during the winter to as much as 70 F (20 C) at midday near the equator.
The carbon-dioxide-rich atmosphere of Mars is also roughly 100 times less dense than Earth's on average, but it is nevertheless thick enough to support weather, clouds and winds. The density of the atmosphere varies seasonally, as winter forces carbon dioxide to freeze out of the Martian air.
NASA’s Mars Reconnaissance Orbiter found the first definitive detections of carbon-dioxide snow clouds, making Mars the only body in the solar system known to host the unusual winter weather. The red planet also causes water-ice snow to fall from the clouds.
The dust storms of the Mars are the largest in the solar system, capable of blanketing the entire red planet and lasting for months. One theory as to why dust storms can grow so big on Mars starts with airborne dust particles absorbing sunlight, warming the Martian atmosphere in their vicinity. Warm pockets of air flow toward colder regions, generating winds. Strong winds lift more dust off the ground, which in turn heats the atmosphere, raising more wind and kicking up more dust.
The carbon-dioxide-rich atmosphere of Mars is also roughly 100 times less dense than Earth's on average, but it is nevertheless thick enough to support weather, clouds and winds. The density of the atmosphere varies seasonally, as winter forces carbon dioxide to freeze out of the Martian air.
NASA’s Mars Reconnaissance Orbiter found the first definitive detections of carbon-dioxide snow clouds, making Mars the only body in the solar system known to host the unusual winter weather. The red planet also causes water-ice snow to fall from the clouds.
The dust storms of the Mars are the largest in the solar system, capable of blanketing the entire red planet and lasting for months. One theory as to why dust storms can grow so big on Mars starts with airborne dust particles absorbing sunlight, warming the Martian atmosphere in their vicinity. Warm pockets of air flow toward colder regions, generating winds. Strong winds lift more dust off the ground, which in turn heats the atmosphere, raising more wind and kicking up more dust.
Orbital characteristics
The axis of Mars, like Earth's, is tilted with relation to the sun. This means that like Earth, the amount of sunlight falling on certain parts of the planet can vary widely during the year, giving Mars seasons.
However, the seasons that Mars experiences are more extreme than Earth's because the red planet's elliptical, oval-shaped orbit around the sun is more elongated than that of any of the other major planets. When Mars is closest to the sun, its southern hemisphere is tilted toward the sun, giving it a short, very hot summer, while the northern hemisphere experiences a short, cold winter. When Mars is farthest from the sun, the northern hemisphere is tilted toward the sun, giving it a long, mild summer, while the southern hemisphere experiences a long, cold winter.
However, the seasons that Mars experiences are more extreme than Earth's because the red planet's elliptical, oval-shaped orbit around the sun is more elongated than that of any of the other major planets. When Mars is closest to the sun, its southern hemisphere is tilted toward the sun, giving it a short, very hot summer, while the northern hemisphere experiences a short, cold winter. When Mars is farthest from the sun, the northern hemisphere is tilted toward the sun, giving it a long, mild summer, while the southern hemisphere experiences a long, cold winter.
Atmospheric composition (by volume)
95.32 percent carbon dioxide, 2.7 percent nitrogen, 1.6 percent argon, 0.13 percent oxygen, 0.08 percent carbon monoxide, minor amounts of water, nitrogen oxide, neon, hydrogen-deuterium-oxygen, krypton, xenon
Magnetic Field
Mars currently has no global magnetic field, but there are regions of its crust that can be at least 10 times more strongly magnetized than anything measured on Earth, remnants of an ancient global magnetic field.
Chemical composition
Mars likely has a solid core composed of iron, nickel, and sulfur. The mantle of Mars is probably similar to Earth's in that it is composed mostly of peridotite, which is made up primarily of silicon, oxygen, iron and magnesium. The crust is probably largely made of the volcanic rock basalt, which is also common in the crusts of the Earth and the moon, although some crustal rocks, especially in the northern hemisphere, may be a form of andesite, a volcanic rock that contains more silica than basalt does.
Internal structure
Scientists think that on average, the Martian core is about 1,800 and 2,400 miles in diameter (3,000 and 4,000 km), its mantle is about 900 to 1,200 miles (5,400 to 7,200 km) wide and its crust is about 30 miles (50 km) thick.
Average distance from the sun
141,633,260 miles (227,936,640 km). By c141,633,260 miles (227,936,640 km). By comparison: 1.524 times that of Earthomparison: 1.524 times that of Earth
Perihelion (closest)
128,400,000 miles (206,600,000 km). By comparison: 1.404 times that of Earth
Aphelion (farthest)
154,900,000 miles (249,200,000 km). By comparison: 1.638 times that of Earth
The moons of Mars
The two moons of Mars, Phobos and Deimos, were discovered by American astronomer Asaph Hall over the course of a week in 1877. Hall had almost given up his search for a moon of Mars, but his wife, Angelina, urged him on — he discovered Deimos the next night, and Phobos six days after that. He named the moons after the sons of the Greek war god Ares — Phobos means "fear," while Deimos means "rout."
Both Phobos and Deimos are apparently made of carbon-rich rock mixed with ice and are covered in dust and loose rocks. They are tiny next to Earth's moon, and are irregularly shaped, since they lack enough gravity to pull themselves into a more circular form. The widest Phobos gets is about 17 miles (27 km), and the widest Deimos gets is roughly nine miles (15 km).
Both moons are pockmarked with craters from meteor impacts. The surface of Phobos also possesses an intricate pattern of grooves, which may be cracks that formed after the impact created the moon's largest crater — a hole about 6 miles (10 km) wide, or nearly half the width of Phobos. They always show the same face to Mars, just as our moon does to Earth.
It remains uncertain how Phobos and Deimos were born. They may have been asteroids captured by Mars' gravitational pull, or they may have been formed in orbit around Mars the same time the planet came into existence. Ultraviolet light reflected from Phobos provides strong evidence for its capture origin, according to astronomers at the University of Padova in Italy.
Phobos is gradually spiraling toward Mars, drawing about 6 feet (1.8 meters) closer to the red planet each century. Within 50 million years, Phobos will either smash into Mars or break up and form a ring of debris around the planet.
Both moons are potential targets for exploration. One NASA plan envisions bombarding Phobos with small, spiky spherical rovers called hedgehogs.
Both Phobos and Deimos are apparently made of carbon-rich rock mixed with ice and are covered in dust and loose rocks. They are tiny next to Earth's moon, and are irregularly shaped, since they lack enough gravity to pull themselves into a more circular form. The widest Phobos gets is about 17 miles (27 km), and the widest Deimos gets is roughly nine miles (15 km).
Both moons are pockmarked with craters from meteor impacts. The surface of Phobos also possesses an intricate pattern of grooves, which may be cracks that formed after the impact created the moon's largest crater — a hole about 6 miles (10 km) wide, or nearly half the width of Phobos. They always show the same face to Mars, just as our moon does to Earth.
It remains uncertain how Phobos and Deimos were born. They may have been asteroids captured by Mars' gravitational pull, or they may have been formed in orbit around Mars the same time the planet came into existence. Ultraviolet light reflected from Phobos provides strong evidence for its capture origin, according to astronomers at the University of Padova in Italy.
Phobos is gradually spiraling toward Mars, drawing about 6 feet (1.8 meters) closer to the red planet each century. Within 50 million years, Phobos will either smash into Mars or break up and form a ring of debris around the planet.
Both moons are potential targets for exploration. One NASA plan envisions bombarding Phobos with small, spiky spherical rovers called hedgehogs.
Research & exploration
The first person to watch Mars with a telescope was Galileo Galilei, and in the century after him, astronomers discovered its polar ice caps. In the 19th and 20th centuries, researchers believed they saw a network of long, straight canals on Mars, hinting at civilization, although later these often proved to be mistaken interpretations of dark regions they saw.
Possibility of life
Mars could have once harbored life. Some conjecture that life might still exist there even today. A number of researchers have even speculated that life on Earth may have seeded Mars, or that life on Mars seeded Earth.
The most public scientific claim for life on Mars came in 1996. Geologist David McKay at NASA's Johnson Space Center in Houston and his colleagues focused on rocks blasted off the surface of Mars by cosmic impacts that landed on Earth. Within they found complex organic molecules, grains of a mineral called magnetite that can form within some kinds of bacteria, and tiny structures that resembled fossilized microbes. However, these claims have proven controversial, and there is no consensus as to whether they are signs of life.
The most public scientific claim for life on Mars came in 1996. Geologist David McKay at NASA's Johnson Space Center in Houston and his colleagues focused on rocks blasted off the surface of Mars by cosmic impacts that landed on Earth. Within they found complex organic molecules, grains of a mineral called magnetite that can form within some kinds of bacteria, and tiny structures that resembled fossilized microbes. However, these claims have proven controversial, and there is no consensus as to whether they are signs of life.
Species overview
Earth is the only planet in the universe known to possess life. There are several million known species of life, ranging from the bottom of the deepest ocean to a few miles into the atmosphere, and scientists think far more remain to be discovered. Scientists figure there are between 5 million and 100 million species on Earth, but science has only identified about 2 million of them.
Earth is the only body in the solar system known to host life, although scientists suspect that other candidates — such as Saturn’s moon Titan or Jupiter’s moon Europa — have the potential to house primitive living creatures. Scientists have yet to precisely nail down exactly how complex life rapidly evolved on Earth from more primitive ancestors. One solution suggests that life first evolved on the nearby planet Mars, once a habitable planet, then traveled to Earth on meteorites hurled from the Red Planet.
Earth is the only body in the solar system known to host life, although scientists suspect that other candidates — such as Saturn’s moon Titan or Jupiter’s moon Europa — have the potential to house primitive living creatures. Scientists have yet to precisely nail down exactly how complex life rapidly evolved on Earth from more primitive ancestors. One solution suggests that life first evolved on the nearby planet Mars, once a habitable planet, then traveled to Earth on meteorites hurled from the Red Planet.
Need To Know
1) Small Planet
If the sun were as tall as a typical front door, Earth would be the size of a nickel, and Mars would be about as big as an aspirin tablet.
2) Fourth Rock
Mars orbits our sun, a star. Mars is the fourth planet from the sun at a distance of about 228 million km (142 million miles) or 1.52 AU.
3) Longer Days
One day on Mars takes just a little over 24 hours (the time it takes for Mars to rotate or spin once). Mars makes a complete orbit around the sun (a year in Martian time) in 687 Earth days.
4) Rugged Terrain
Mars is a rocky planet, also known as a terrestrial planet. Mars' solid surface has been altered by volcanoes, impacts, crustal movement and atmospheric effects such as dust storms.
5) Bring a Spacesuit
Mars has a thin atmosphere made up mostly of carbon dioxide (CO2), nitrogen (N2) and argon (Ar).
6) Double Moons
Mars has two moons named Phobos and Deimos.
7) Ringless
There are no rings around Mars.
8) Many Missions
Several missions have visited this planet, from flybys and orbiters to rovers on the surface of the Red Planet. The first true Mars mission success was Mariner 4 in 1965.
9) Tough Place for Life
At this time in the planet's history, Mars' surface cannot support life as we know it. Current missions exploring Mars on the surface and from orbit are determining Mars' past and future potential for life.
10) Rusty Planet
Mars is known as the Red Planet because iron minerals in the Martian soil oxidize, or rust, causing the soil -- and the dusty atmosphere -- to look red.
In Depth
Though details of Mars' surface are difficult to see from Earth, telescope observations show seasonally changing features and white patches at the poles. For decades, people speculated that bright and dark areas on Mars were patches of vegetation, Mars was a likely place for advanced life forms, and water might exist in the polar caps. When the Mariner 4 spacecraft flew by Mars in 1965, photographs of a bleak, cratered surface shocked many - Mars seemed to be a dead planet. Later missions, however, showed that Mars is a complex planet and holds many mysteries yet to be solved. Chief among them is whether Mars ever had the right conditions to support small life forms called microbes.
Mars is a rocky body about half the size of Earth. As with the other terrestrial planets - Mercury, Venus, and Earth - volcanoes, impact craters, crustal movement, and atmospheric conditions such as dust storms have altered the surface of Mars.
Mars has two small moons, Phobos and Deimos, that may be captured asteroids. Potato-shaped, they have too little mass for gravity to make them spherical. Phobos, the innermost moon, is heavily cratered, with deep grooves on its surface
Like Earth, Mars experiences seasons due to the tilt of its rotational axis. Mars' orbit is about 1.5 times farther from the sun than Earth's and is slightly elliptical, so its distance from the sun changes. That affects the length of Martian seasons, which vary in length. The polar ice caps on Mars grow and recede with the seasons. Layered areas near the poles suggest that the planet's climate has changed more than once. Volcanism in the highlands and plains was active more than 3 billion years ago. Some of the giant shield volcanoes are younger, having formed between 1 and 2 billion years ago. Mars has the largest volcano in the solar system, Olympus Mons, as well as a spectacular equatorial canyon system, Valles Marineris.
Mars has no global magnetic field today. However, NASA's Mars Global Survey ororbiter found that areas of the Martian crust in the southern hemisphere are highly magnetized, indicating traces of a magnetic field from 4 billion years ago that remain.
Scientists believe that Mars experienced huge floods about 3.5 billion years ago. Though we do not know where the ancient flood water came from, how long it lasted, or where it went, recent missions to Mars have uncovered intriguing hints. In 2002, NASA's Mars Odyssey orbiter detected hydrogen-rich polar deposits, indicating large quantities of water ice close to the surface. Further observations found hydrogen in other areas as well. If water ice permeated the entire planet, Mars could have substantial subsurface layers of frozen water. In 2004, Mars Exploration Rover Opportunity found structures and minerals indicating that liquid water once existed at its landing site. The rover's twin, Spirit, also found the signature of ancient water near its landing site, halfway around Mars from Opportunity's location.
The cold temperatures and thin atmosphere on Mars do not allow liquid water to exist at the surface for long. The quantity of water required to carve Mars' great channels and flood plains is not evident today. Unraveling the story of water on Mars is important to unlocking its climate history, which will help us understand the evolution of all the planets. Water is an essential ingredient for life as we know it. Evidence of long-term past or present water on Mars holds clues about whether Mars could ever have been a habitat for life.
In 2008, NASA's Phoenix Mars lander was the first mission to touch water ice in the Martian arctic. Phoenix also observed precipitation (snow falling from clouds), as confirmed by Mars Reconnaissance Orbiter. Soil chemistry experiments led scientists to believe that the Phoenix landing site had a wetter and warmer climate in the recent past (the last few million years). NASA's Mars Science Laboratory mission, with its large rover Curiosity, is examining Martian rocks and soil at Gale Crater, looking for minerals that formed in water, signs of subsurface water, and carbon-based molecules called organics, the chemical building blocks of life. That information will reveal more about the present and past habitability of Mars, as well as whether humans could survive on Mars some day.
How Mars Got its Name
Mars was named by the Romans for their god of war because of its red, bloodlike color. Other civilizations also named this planet from this attribute; for example, the Egyptians named it "Her Desher," meaning "the red one."
Significant Dates
- 1877: Asaph Hall discovers the two moons of Mars, Phobos and Deimos.
- 1965: NASA's Mariner 4 sends back 22 photos of Mars, the world's first close-up photos of a planet beyond Earth.
- 1976: Viking 1 and 2 land on the surface of Mars.
- 1997: Mars Pathfinder lands and dispatches Sojourner, the first wheeled rover to explore the surface of another planet.
- 2002: Mars Odyssey begins its mission to make global observations and find buried water ice on Mars.
- 2004: Twin Mars Exploration Rovers named Spirit and Opportunity find strong evidence that Mars once had long-term liquid water on the surface.
- 2006: Mars Reconnaissance Orbiter begins returning high-resolution images as it studies the history of water on Mars and seasonal changes.
- 2008: Phoenix finds signs of possible habitability, including the occasional presence of liquid water and potentially favorable soil chemistry.
- 2012: NASA's Mars rover Curiosity lands in Gale Crater and finds conditions once suited for ancient microbial life on Mars.
Sources
- www.space.com
- www.nasa.gov
Note: All the information from this page is current to 2016, information can change in the future years to come
