Mars Facts

All Mars Facts

Mars is named after the Roman god of war, likely because its reddish color reminded ancient observers of blood.
Ancient Egyptians called Mars "Her Desher," meaning "the red one," thousands of years before telescopes existed.
A day on Mars, called a "sol," lasts about 24 hours and 37 minutes, only slightly longer than a day on Earth.
A year on Mars lasts about 687 Earth days, almost twice as long as an Earth year.
Mars has a diameter of about 4,220 miles (6,779 km), roughly half the diameter of Earth.
Mars's gravity is about 38% of Earth's, so a 150-pound person would weigh only about 57 pounds there.
Even though Mars is much smaller than Earth, its total land surface area is roughly comparable to Earth's, since Mars has no oceans.
Mars orbits the Sun at an average distance of about 142 million miles (228 million km).
At its closest recorded approach in 2003, Mars came within about 34.6 million miles of Earth, the nearest in nearly 60,000 years.
Mars's axial tilt of about 25 degrees is close to Earth's, which is why it has four seasons much like our planet.
Because a Martian year is so much longer than Earth's, each Martian season lasts roughly twice as long as its Earth counterpart.
Mars's orbit is noticeably more elliptical than Earth's, so its distance from the Sun varies more sharply over the Martian year.
Mars's atmosphere is about 95% carbon dioxide, with only trace amounts of oxygen and water vapor.
The atmospheric pressure on Mars is less than 1% of Earth's, too thin to support liquid water on the surface today.
Because Mars's atmosphere is so thin, it traps very little heat, causing huge temperature swings between day and night.
Temperatures near the Martian poles can plunge to about -195°F (-125°C) in winter.
On a warm summer day near the Martian equator, temperatures can briefly reach around 70°F (20°C).
Daytime skies on Mars often appear butterscotch or reddish, tinted by fine iron oxide dust suspended in the thin atmosphere.
Sunsets on Mars can look bluish, the opposite of Earth, because Martian dust scatters light differently than our atmosphere does.
Mars does not have a global magnetic field today, though patches of magnetized rock in its crust show it once did billions of years ago.
Scientists think the loss of Mars's magnetic field let solar wind gradually strip away most of its once-thicker atmosphere.
Olympus Mons, the largest volcano on Mars, stands about 13.6 miles (22 km) high, nearly three times the height of Mount Everest.
Olympus Mons is so wide at its base that it would cover an area roughly the size of the state of Arizona.
Olympus Mons is a shield volcano, built up gradually by countless lava flows rather than a single explosive eruption.
Three more giant volcanoes, Arsia Mons, Pavonis Mons, and Ascraeus Mons, line up in a row on Mars's Tharsis plateau.
Valles Marineris, a canyon system on Mars, stretches roughly 2,500 miles long, nearly the width of the continental United States.
In places, Valles Marineris plunges as deep as 4.3 miles (7 km), more than seven times deeper than Earth's Grand Canyon.
Hellas Planitia is a massive impact basin on Mars, one of the largest confirmed impact craters in the entire solar system.
Mars has two polar ice caps that grow and shrink with the seasons as frozen carbon dioxide comes and goes.
Beneath its seasonal frost, Mars's northern polar cap holds a thick layer of water ice.
Mars's southern polar cap keeps a permanent layer of frozen carbon dioxide, often called "dry ice," year-round.
Mars has clouds too, made of water ice or, at times, of frozen carbon dioxide crystals.
Dust devils, small spinning columns of wind and dust, regularly sweep across the Martian surface and have even been photographed from orbit.
Mars occasionally experiences planet-encircling dust storms so vast they can block sunlight across the entire globe for weeks.
A global dust storm in 2018 blotted out so much sunlight that it silenced NASA's solar-powered Opportunity rover for good.
Global Martian dust storms tend to strike during southern hemisphere summer, when Mars is closest to the Sun in its elliptical orbit.
The Martian south pole is home to strange "spider" patterns in the ground, carved as trapped carbon dioxide ice turns directly to gas each spring.
Mars has two small moons, Phobos and Deimos, both thought to be either captured asteroids or debris from an ancient impact.
Phobos and Deimos are named after the sons of Ares, the Greek god of war, whose names mean "fear" and "dread."
Phobos orbits Mars so quickly, about three times a day, that it appears to rise in the west and set in the east.
Phobos is slowly spiraling inward toward Mars and is expected to eventually break apart or crash into the planet within tens of millions of years.
Deimos, the smaller and more distant of Mars's two moons, is lumpy and irregularly shaped rather than round.
Neither Martian moon is large enough for its own gravity to pull it into a spherical shape.
Ancient river channels and fan-shaped deltas etched into the Martian surface suggest liquid water once flowed there in abundance.
Some scientists believe Mars's northern lowlands may once have held a vast ocean, billions of years before the planet dried out.
NASA's Opportunity rover found small mineral spheres nicknamed "blueberries," made of hematite that typically forms in the presence of water.
NASA's Phoenix lander confirmed water ice just beneath the Martian soil near the north pole in 2008.
Radar studies have detected large deposits of water ice hidden underground across many regions of Mars.
Dark streaks called recurring slope lineae appear and grow on some Martian crater walls during warm seasons, though scientists still debate whether they involve any liquid water.
Gullies carved into some Martian crater walls hint that liquid water, or perhaps carbon dioxide frost, may still shape the surface occasionally today.
NASA's Curiosity rover has detected organic molecules, the carbon-based building blocks of life, preserved in ancient Martian rocks.
Curiosity has also measured methane in the Martian atmosphere that mysteriously rises and falls with the seasons, and its source is still unknown.
In 2021, the Perseverance rover's MOXIE instrument successfully produced breathable oxygen from Mars's carbon dioxide atmosphere for the first time.
NASA's InSight lander detected marsquakes on Mars, revealing that the planet still has a molten, at least partly liquid, core.
Seismic data from InSight suggests Mars's core has a radius of roughly 1,140 miles, larger than scientists had previously estimated.
Mariner 4 became the first spacecraft to fly past Mars in 1965, returning the first close-up images ever taken of another planet.
Mariner 9 became the first spacecraft to orbit another planet when it reached Mars in 1971.
The Soviet Mars 3 mission achieved the first soft landing on Mars in 1971, but its lander transmitted for only about 20 seconds before falling silent.
NASA's Viking 1 became the first fully successful lander on Mars in 1976, operating on the surface for more than six years.
The Viking landers carried out experiments specifically designed to search for microbial life in Martian soil, though results were inconclusive.
So many early Mars missions failed that space enthusiasts nicknamed the run of bad luck the "Great Galactic Ghoul."
Roughly half of all Mars missions ever attempted, across every space agency, have ended in partial or total failure.
NASA lost its Mars Climate Orbiter in 1999 after one engineering team used metric units and another used imperial units for the same calculations.
The British Beagle 2 lander was presumed lost after its 2003 landing, until orbital images found it intact on the surface more than a decade later.
Sojourner, the first rover to operate on Mars in 1997, was roughly the size of a microwave oven.
NASA's Spirit and Opportunity rovers landed on Mars in 2004, each designed for a 90-day mission.
Opportunity kept exploring Mars for almost 15 years before a global dust storm finally ended communication with it in 2018.
Spirit became stuck in soft Martian soil in 2009 and eventually stopped communicating with Earth in 2010.
Curiosity, roughly the size of a small car, landed inside Mars's Gale Crater in 2012 using a rocket-powered "sky crane."
Curiosity's main science target, Mount Sharp, is a layered mountain of sediment rising from the floor of Gale Crater.
Both Curiosity and Perseverance run on nuclear power from a radioisotope generator, letting them keep working without relying on sunlight.
Earlier solar-powered rovers like Spirit and Opportunity gradually lost power as dust settled on their solar panels over time.
NASA's Perseverance rover landed in Jezero Crater in 2021, a site chosen because it holds the remains of an ancient river delta.
Perseverance is drilling and caching rock samples on Mars for a future mission designed to bring them back to Earth for study.
Perseverance carries microphones that have recorded the actual sound of Martian wind and the rover's own mechanical clicks and whirs.
Because Mars's atmosphere is thin and mostly carbon dioxide, sound there travels more quietly and higher-pitched tones fade out faster than on Earth.
In April 2021, NASA's Ingenuity helicopter made the first powered, controlled flight ever achieved on another planet.
Ingenuity had to spin its rotor blades far faster than any helicopter on Earth to generate lift in Mars's thin atmosphere.
Ingenuity flew 72 flights on Mars before rotor damage grounded it for good in early 2024, far outlasting its planned five-flight test campaign.
China's Zhurong rover touched down on Mars in 2021 as part of the Tianwen-1 mission, making China only the second country to land and operate a rover there.
The United Arab Emirates' Hope probe entered orbit around Mars in 2021, becoming the first Mars mission led by an Arab nation.
The European Space Agency's Mars Express orbiter has been studying the planet continuously since 2003.
NASA's Mars Reconnaissance Orbiter carries the HiRISE camera, sharp enough to spot surface features smaller than a yard across from orbit.
More than 300 meteorites found on Earth have been identified as originating from Mars, blasted into space by ancient asteroid or comet impacts.
A Martian meteorite found in Antarctica in 1984, known as ALH84001, once sparked controversy when some scientists suggested it held fossilized microbial life, a claim now widely disputed.
Mars has at least five known trojan asteroids, small bodies that share its orbit around the Sun.
Mars is bright enough to see with the naked eye from Earth and has been observed by skywatchers since ancient times.
Babylonian astronomers associated Mars with Nergal, their god of war and plague, thousands of years ago.
In Hindu astrology, Mars is known as Angaraka or Mangala and is tracked as one of the classical navagraha bodies.
Mars's puzzling retrograde motion in the night sky, appearing to move backward at times, helped inspire ancient debates that eventually led to the heliocentric model of the solar system.
A trip to Mars with current propulsion technology takes roughly seven months one way.
Because Mars and Earth orbit the Sun at different speeds, launch windows to Mars only open up roughly once every 26 months.
NASA and other agencies are studying future crewed missions to Mars, though no human has yet set foot on the planet.
SpaceX has designed its Starship rocket with the long-term goal of eventually carrying astronauts and cargo to Mars.
Researchers use extreme places on Earth, like Antarctica's Dry Valleys and Chile's Atacama Desert, as stand-ins for testing Mars exploration technology and searching for life in Mars-like conditions.
Because Mars lacks an ozone layer, its surface receives far more damaging ultraviolet radiation than Earth's does.
Mars's thin atmosphere and lack of a magnetic field mean the surface is also bathed in more cosmic radiation than Earth, a major challenge for future astronauts.
Mars has no moons large enough to stabilize its axial tilt the way Earth's Moon does, so its tilt is thought to have wandered more dramatically over millions of years.
Mars's iconic red-orange color comes from iron oxide, essentially rust, coating fine dust across most of its surface.
Beneath its rusty dust, much of the actual bedrock on Mars is grey or black basalt, similar to volcanic rock found on Earth.
Some regions of Mars, like the Medusae Fossae Formation, are covered in soft, easily eroded material that wind has carved into strange ridges and grooves.
Mars's craters range from tiny pits to Hellas Planitia, which measures roughly 1,300 miles across.
Mars is a favorite target for amateur astronomers because it can be viewed through a modest backyard telescope during its closest approaches to Earth.
Mars has surface gravity of about 3.72 meters per second squared, well under half of Earth's 9.8.
A Martian year lasts roughly 668 to 669 Martian sols, even though it equals about 687 Earth days.
The Perseverance rover's landing site, Jezero Crater, was once filled by a lake fed by a river that deposited a fan-shaped delta still visible today.
Mars's two moons are so small that Phobos is only about 14 miles across and Deimos just 7.7 miles across at their longest points.
Because Deimos orbits so far out and slowly, it would appear from the Martian surface as little more than a bright, star-like point of light.
The word "areology" is sometimes used for the geological study of Mars, borrowing from Ares, the Greek name for the god of war.
Mars has been visited or observed by robotic missions from the United States, the Soviet Union/Russia, Europe, India, China, Japan, and the United Arab Emirates.

All Mars Facts

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