Mars Facts for Kids

The red planet is dusty, cold world with a thin atmosphere and is home to four NASA robots.

Mars is named after the Roman god of war. For the Greeks, Mars was known as Ares. It was named after the god of war because of its red color.

Key Facts & Summary

  • Mars is the fourth planet from the Sun and the second-smallest planet of the Solar System.
  • Mars is the most widely searched planet for life, inspiring many works of fiction.
  • The first person to observe Mars with the use of a telescope was Galileo Galilei. He observed the Red Planet in 1610.
  • Mars is 227.9 million kilometers / 141.6 million miles away from the Sun.
  • Light from the Sun reaches Mars in about 13 minutes.
  • Mars is around two times smaller than Earth. It has a diameter of 6.779 km / 4.212 mi.
  • Mars is around 10 times less massive than Earth.
  • Mars is the outermost terrestrial planet, outside Earth’s orbit. It is 50% farther away from the Sun than Earth.
  • Mars has two known natural satellites, Phobos and Deimos.
  • Phobos is predicted to suffer a collision with Mars in the distant future.
  • The atmosphere on Mars is thin, mostly comprised of carbon dioxide, nitrogen, and argon gases.
  • The tallest volcano/mountain in the Solar System is located on Mars. It is named Olympus Mons and it seems to have a height of 21 km / 13 mi.
  • Mars also has the biggest canyon in the Solar System. It is named Valles Marines. It is 4.000 km / 2.500 mi long and reaches depths of 7 km / 4 mi deep. The Grand Canyon on Earth is only 446 km / 226 mi long, and only 1.6 km / 1 mi deep.
  • Mars doesn’t have a magnetic field however some areas are highly magnetized.
  • The average temperatures on Mars is -80 degrees Fahrenheit / -60 degrees Celsius.
  • Mars represents masculinity and the symbol of the planet is used for the male gender.

Mars is widely known as the Red planet. Its reddish appearance is caused by the presence of rusty iron in the ground. The name of the month March is derived from Mars.

Mars is visible to the naked eye, and as such, you can see it without the use of a telescope or binoculars. The Red planet is very similar to Earth, and scientists are trying to find out if life was present there.

Surface and Structure

In many ways, Mars can be considered Earth’s brother. It has seasons, polar ice caps, volcanoes, canyons, and weather. There are many signs of ancient floods on the Red Planet, but now water mostly exists in icy dirt and thin clouds.

There is evidence of liquid salty water in the ground, especially on hillsides. This may be great if people will go there in the future, but observations continue.

Mars is the seventh-largest planet of the Solar System and the fourth planet from the Sun. It has the most varied and complex terrain than any of the terrestrial planets, except for Earth.

On Mars’s surface, we have discovered the biggest mountain in the Solar System. It is named Olympus Mons, and it is three times bigger than the largest mountain on Earth, Everest.

Another great feature of Mars is Valles Marineris, a network of canyons that run 4.000 km / 2.485 mi long and stand from 2 to 7 km / 1 to 4 mi tall.

Hellas Planitia is a huge crater on Mars created from an ancient impact. It is located on the Red Planet’s southern hemisphere and its over 6 km / 3.7 mi deep and 2.000 km / 1.242 mi across.

Oceans and lakes may have existed on Mars long ago, but it seems that water was only around for a short period. Some believe that water exists underneath Mars’s surface.

There are many differences in Mars’s southern and northern hemispheres. For example, in the southern hemisphere, many ancient cratered highlands are present, similar to the ones on the Moon.

In the northern hemisphere, plains have undergone changes since the planet formed long ago, and this hemisphere is also lower in elevation.

Time on Mars

A day on Mars is a little longer than a day on Earth. It lasts about 24.6 hours. A year on Mars, however, or the time that takes for the Red Planet to circle our Sun, lasts about 687 Earth days or almost twice as long as a year on Earth.

Fun Facts

  1. Mars has seasons just like Earth, but they last longer. This is because it takes longer for it to orbit the Sun. The seasons vary in length since Mars has an egg-shaped orbit around the Sun.
  2. The longest season on Mars is spring, which lasts for 194 days. Autumn is the shortest lasting only 142 days.
  3. Occasionally, winds on Mars are strong enough to create dust storms. It takes months for all the dust to settle, and this is a great impediment for the space probes sent there.
  4. Mars doesn’t have a ring system like Saturn. However, one of its moons, Phobos, will crash on Mars in the distant future and this may create a ring system around the Red Planet.
  5. Many observations and analyses indicate that Mars was once very similar to Earth, having water or even whole oceans.
  6. If you stood on Mars and looked at the Sun, it would appear about half the size as we see it on Earth.
  7. Pieces of Mars have fallen on Earth. Scientists are studying these materials to this day.
  8. If you would weigh 100kg on Earth, on Mars you would weigh 38kg because Mars’s gravity is only 38% that of Earth.
  9. Around six Mars-sized planets would fit the volume of Earth. However, it would take 7 million Mars-sized planets to fill the volume of the Sun.
  10. A book written by Jonathan Swift mentioned the two moons of Mars 151 years before they were actually discovered.
  11. Some believe that the Valles Marines on Mars is the result of a huge collision.

Size and Comparison

Mars is and the second-smallest planet of the Solar System after Mercury, having a diameter of 6.779 km / 4.212 mi. It is 30% bigger than Mercury and almost two times smaller than Earth and Venus.

Neptune and Uranus have around 7.2 times the diameter of Mars. Saturn, on the other hand, has 17.1 times its diameter. But the biggest planet in the Solar System is Jupiter, and it has more than 20 times the diameter of Mars.


Life on Mars

Throughout much of the  19th century, it was believed that life on Mars existed partly due to a mistake. An astronomer believed that he observed straight lines on Mars’ surface.

Many believed that this could only be the work of intelligent life as the straight lines resembled canals for irrigation purposes. However, as more advanced telescopes were built and observations on Mars’s surface were more accurate – it was revealed that the straight lines were an optical illusion.

Mars and Venus atmosphere similarity

If Mars is among the most hospitable planets, Venus is among the most inhospitable. However, their atmosphere is similar in regards to one component – carbon dioxide – 95% for Mars, 97% for Venus.

However, the main difference is that Venus’s greenhouse effect traps temperatures at around 480 degrees Celsius, while Mars doesn’t exceed 20 degrees Celsius.

Other Characteristics

Mars has a thin but active atmosphere. The surface of the Red Planet isn’t active, however, its volcanoes are dead. The atmosphere on Mars is made of carbon dioxide, nitrogen, and argon.

The planets closest to Mars, its neighbors, are Earth and Jupiter. Mars also has two moons, Phobos and Deimos. They are smaller than Earth’s moon.

Phobos is slowly descending upon Mars, and scientists believe that one day it will crash on the Red Planet. Mars is the outermost terrestrial planet, almost 50% farther from the Sun than Earth.

Many missions were sent to Mars, so many that the Red Planet is theoretically populated with robots. Some projects here on Earth, want to colonize the Red Planet, beginning in 2022.

Mars Notes

  • Mars is a small planet, cold, and as far as we know, lifeless. However, it is the most hospitable planet in the Solar System, second only to Earth.
  • The first spacecraft to visit Mars was Mariner 4, this happened in 1965.
  • Mars has ice caps at both poles made up of solid carbon dioxide or dry ice.
  • Powerful dust storms and winds blow through the entire planet for months.
  • There are high chances that people will one day colonize the Red Planet.
  • Though Mars can become our second Earth, one of the biggest issues is gravity. The gravity on Mars can cause bone damage.


[1.] NASA

[2.] Wikipedia

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