Mars: The Red Planet

Every day, we discover more about the fourth rock from the sun.


Mars is the planet closest to the sun. The Romans dubbed the Red Planet after their god of war, fitting the planet's red tint. The Romans, in fact, copied the ancient Greeks, who called the planet Ares after their god of war.

Other civilizations named the planet after its hue, such as the Egyptians who called it "Her Desher," which means "the red one," and ancient Chinese scientists who called it "the fire star."

Several unmanned spacecraft have visited Mars. Mariner 4 was the first spacecraft to visit Mars, arriving on the planet on July 15, 1965, after being launched by NASA on November 28, 1964. Mariner 4 discovered the weak Martian radiation belt, which is only 0.1 percent that of Earth, and took the first deep-space photos of another planet. The Soviet Mars 3 mission comprised a lander that made a soft landing in December 1971, but communication was lost seconds later. Viking 1 made the first successful landing on the Martian surface on July 20, 1976.

The Mars Pathfinder spacecraft landed on Mars on July 4, 1997, and on July 5, its rover, Sojourner, the first robotic rover to operate on Mars, was unleashed. On December 25, 2003, the Mars Express orbiter, the first European Space Agency (ESA) spacecraft to visit Mars, was launched into orbit. Spirit and Opportunity, NASA's Mars Exploration Rovers, landed on Mars in January 2004; Spirit worked until March 22, 2010, and Opportunity until June 10, 2018.

Mars is about 230 million km (143 million mi) from the Sun; its orbital period is 687 (Earth) days, depicted in red. Earth's orbit is in blue.

NASA's Curiosity rover touched down on Mars on August 6, 2012, as part of its Mars Science Laboratory (MSL) mission to study the planet's environment and geology. When its maiden interplanetary mission, the Mars Orbiter Mission spacecraft, arrived in orbit on September 24, 2014, the Indian Space Research Organisation (ISRO) became the fourth space agency to visit Mars. On February 9, 2021, the United Arab Emirates became the fifth country to successfully launch a mission to Mars, inserting an orbiter into the Martian atmosphere.

The Tianwen-1 spacecraft of China's National Space Program Administration (CNSA) entered Martian orbit on February 10, 2021. On February 18, 2021, NASA's Perseverance rover and Ingenuity helicopter successfully landed on Mars. On April 19, 2021, Ingenuity conducted the first powered controlled flight by an aircraft outside of Earth, lifting off vertically, hovering, and landing on Mars. CNSA's Tianwen-1 lander and Zhurong rover successfully landed on Mars on May 14, 2021. The Zhurong rover was successfully deployed on Mars on May 22, 2021, becoming China the second country after the United States to do it.

The Mars Information is and will be going to added


Because Mars is farther away from the sun than Earth, it has a longer year – 687 days compared to 365 for our home planet. The two planets, however, have identical day lengths; Mars takes around 24 hours and 40 minutes to complete one rotation around its axis, whereas Earth takes 24 hours.
Mars, like Earth, has a tilted axis in reference to the sun. This means that, like Earth, the quantity of sunlight falling on different portions of Mars varies greatly throughout the year, resulting in Mars seasons.
The seasons on Mars, however, are more harsh than those on Earth due to the Red Planet's elliptical, oval-shaped orbit around the sun, which is longer than any of the other main planets. When Mars is closest to the sun, its southern hemisphere is angled toward our star, resulting in a short, warm summer for the planet and a short, frigid winter for the northern hemisphere. The northern hemisphere of Mars is inclined toward the sun when it is farthest from the sun, giving it a long, pleasant summer, while the southern hemisphere has a long, cold winter.

Equatorial Diameter: 6,792 km
Polar Diameter: 6,752 km
Mass: 6.39 × 10^23 kg (0.11 Earths)
Moons: 2 Phobos and Deimos
Orbit Distance: 227,943,824 km (1.38 AU)
Orbit Period: 687 days (1.9 years)
Surface Temperature: -87 to -5 °C
Discovered by Egyptian astronomers
First Discovered 2nd millennium BC


Mars is a difficult planet to reach. In their attempt to investigate Mars, NASA, Russia, the European Space Agency, China, Japan, and the Soviet Union together lost many spacecraft. Among the most notable examples are (but are not limited to):

1992 NASA's Mars Observer
1996 Russia's Mars 96
1998 NASA's Mars Climate Orbiter, Japan's Nozomi
1999 NASA's Mars Polar Lander
2003 ESA's Beagle 2 lander
2011 Russia's Fobus-Grunt mission to Phobos, with the Chinese Yinghuo-1 orbiter
2016 ESA's Schiaparelli test lander

Mars Moon

In 1877, American astronomer Asaph Hall discovered the two moons of Mars, Phobos and Deimos, over the course of a week. Hall was on the verge of abandoning his hunt for a Martian moon when his wife, Angelina, persuaded him to keep on. The next night, he discovered Deimos, and six days later, Phobos. Phobos means "fear," and Deimos means "rout." He named the moons after the sons of Ares, the Greek battle god.

Phobos (about 22 kilometres (14 mi) in diameter) and Deimos (approximately 12 kilometres (7.5 mi) in diameter) are two natural moons of Mars that orbit close to the planet. Asteroid capture has long been a popular notion, but its genesis is unknown. Asaph Hall discovered both satellites in 1877, and they are named after the Greek mythological characters Phobos (fear) and Deimos (terror/dread), who accompanied their father Ares, the god of war, into battle. Ares' Roman counterpart was Mars. The planet's old name, Ares (Aris: ), is still used in modern Greek.

Both Phobos and Deimos are covered in dust and loose boulders and appear to be comprised of carbon-rich rock combined with ice. They are small in comparison to Earth's moon and unevenly shaped due to a lack of gravity that allows them to pull themselves into a more round shape. Phobos is about 17 miles (27 kilometers) wide, while Deimos is around 9 miles wide (15 km). (The moon is 2,159 miles (3,475 kilometers) across.)

Orbit of Moon

Meteor strikes have left craters on both of Mars' moons. The moon's surface also has an elaborate network of grooves, which could be fissures that formed after the impact that caused the moon's greatest crater – a hole roughly half the breadth of Phobos. The two Martian satellites, like our moon, constantly present the same face to their home planet.

It's still unclear how Phobos and Deimos came to be. They could be caught asteroids grabbed by Mars' gravitational pull, or they could have originated in orbit around Mars around the same time as the planet. According to researchers at the University of Padova in Italy, ultraviolet light reflected from Phobos gives significant evidence that the moon is a captured asteroid.

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.


By Lookang many thanks to author of original simulation = Todd K. Timberlake author of Easy Java Simulation = Francisco Esquembre - Own work, CC BY-SA 3.0,