Mars is one of the most explored bodies in the solar system, and it’s the only planet we’ve sent rovers to roam the alien landscape. The fourth planet from the Sun, Mars is a cold desert world with evidence of ancient floods. This dynamic planet has seasons, polar ice caps, volcanoes, and weather.
Size and Distance
Mars is about half the size of Earth, with a radius of 2,106 miles (3,390 kilometers).
- From an average distance of 142 million miles (228 million kilometers), Mars is 1.5 astronomical units away from the Sun.
- One astronomical unit (AU) is the distance from the sun to Earth.
Orbit and Rotation
As Mars orbits the Sun, it completes one rotation every 24.6 hours, which is very similar to one day on Earth.
- Martian days are called sols — short for “solar day.”
- A year on Mars lasts 669.6 sols, the same as 687 Earth days.
Atmosphere
A thin atmosphere made up mostly of carbon dioxide, nitrogen and argon gases.
- The temperature on Mars can be as high as 70 degrees Fahrenheit (20 degrees Celsius) or as low as about -225 degrees Fahrenheit (-153 degrees Celsius).
- Because the atmosphere is so thin, heat from the Sun easily escapes this planet.
Formation
When the solar system settled into its current layout about 4.5 billion years ago, Mars formed when gravity pulled swirling gas and dust in to become the fourth planet from the Sun.
- About half the size of Earth, it has a central core, a rocky mantle and a solid crust.
Potential for Life
Mars has two small moons, Phobos and Deimos, that may be captured asteroids
- They’re potato-shaped because they have too little mass for gravity to make them spherical
- The moons get their names from the horses that pulled the chariot of Ares, the Greek god of war
- Phobos means “flight” and deimos means “fear” in ancient Greek
- Oddly-shaped Deimoos is covered in loose dirt that often fills the craters on its surface
Structure
Mars has a dense core at its center between 930 and 1,300 miles (1,500 to 2,100 kilometers) in radius. It’s made of iron, nickel and sulfur.
- Surrounding the core is a rocky mantle between 770- 1,170 miles (240-1,240 to 1,880 kilometers) thick, and above that, a crust that is 6-30 miles (10-10 to 50 kilometers) deep.
Surface
The Red Planet is actually many colors. At the surface we see colors such as brown, gold and tan. The reason Mars looks reddish is due to oxidization and rusting or rusting of iron in the rocks, regolith (Martian “soil”), and dust.
- Interestingly, while Mars is about half the diameter of Earth, its surface has nearly the same area as Earth’s dry land.
