Mars is the fourth planet from the Sun and is one of the closest neighbours to Earth. It is quite small in size (radius = 3390 km), but has an atmosphere very similar to that of Earth.
It is also known as the “red planet”. The red color of its surface is caused by oxidized iron in its atmosphere.
The surface of Mars
The surface of Mars is a mix of rock, dust and soil. It contains carbon-dioxide and traces of oxygen, methane, nitrogen and other gases.
Like Earth, it has a thin atmosphere and a complex weather system. The Martian air is 95% carbon dioxide and has traces of water vapor.
Scientists have been studying the Martian surface since the 1970s. Early spacecraft missions such as Mariner 4 and Viking 1 took pictures of the planet.
Now, researchers are learning more about its interior using a seismometer. That information will help them understand the planet’s core, says NASA Jet Propulsion Laboratory geophysicist Mark Panning.
Seismic readings give scientists the first direct information on a planet’s structure. That’s a big deal, he says.
The atmosphere of Mars
Mars is a planet that has lost most of its atmosphere to space over the course of a few hundred million years. But its thin atmosphere is still a significant source of heat.
The atmosphere on Mars is so thin that it exerts a pressure of less than one percent of Earth’s standard sea-level air pressure. It’s also extremely rarefied, varying with altitude over a factor of 15.
Dust is an important component of the Martian atmosphere. It absorbs visible and infrared light, and reradiates some of it.
These particles are generally 1.4 to 1.7 micrometers (millionths of a meter) in diameter. Larger dust particles, up to 2.5 micrometers in size, have been detected during dust storms.
Dust is very important in driving the wide scale circulation of the Hadley cell on Mars. It has a great influence on the lower and upper atmospheric momentum and heat flows.
The Sun on Mars
The Sun comes and goes in a blue glow on Mars. This color isn’t due to the planet’s atmosphere; rather, it’s caused by how particles in Martian dust scatter sunlight differently than gases do on Earth.
Like the other planets in our solar system, Mars is farther away from the Sun than Earth. Because of this, it takes longer for light to reach Mars – 687 days compared to 365 on Earth.
Because of its elongated orbit, the distance between the Sun and Mars can vary greatly from year to year. That’s why Mars has seasons and different climates on its surface.
The surface of Mars is dotted with polar ice caps and mountains, which help to cool the atmosphere. In addition, the Red Planet is shaped by water and wind. But it also has some major geological features that are unique to it, such as volcanoes and canyons.
The Moon on Mars
Mars has two small moons, called Phobos and Deimos. They orbit the planet close to each other and are considered captured asteroids that crashed into Mars after straying too close.
Both are shaped like potatoes and pitted with a variety of craters. A large impact on Mars may have caused both moons to be shaped that way, and scientists are still trying to understand the process of planetary formation.
In the future, NASA plans to send a spacecraft on a mission to explore both of these moons, called the Martian Moons eXploration (MMX) mission. This mission would collect scientific data and a sample from one of the moons to return to Earth.