The largest volcano in the Solar System can be found on Mars. Olympus Mons rises 27 kilometres from the ground, equivalent to about three of Earth’s Mount Everests!
Mars is known as the red planet and it is easy to see why. When you look up at the night sky Mars appears red, while pictures from spacecraft that have landed on Mars are of a landscape covered in red dust. Believe it or not, Mars is red because it is rusty. No, really! The dust on Mars is mainly made up of rusted iron that is combined with water – scientists believe that in the distant past Mars may have had seas, lakes and rivers. The red dust also gets into Mars’ atmosphere, making the sky on Mars look pink!
So where did all the water go? Today, Mars is too cold to have liquid water.
Remember the Goldilocks Zone that we talked about? Mars’ orbit is just outside of this zone. Mars has two large ice caps at its poles, and also huge amounts of ice just below the surface. Satellites orbiting around Mars have photographed ice and frost in craters. The latest robot to touch down on Mars, called Phoenix, landed near the north pole and has found ice underneath a thin layer of dust and dirt. It is thought that hundreds of millions, or even billions of years ago, Mars was warmer because it had a thicker atmosphere to trap some of the Sun’s heat. Now that atmosphere has gone, the average temperature on Mars these days is –63 degrees Celsius, and it can get as cold as –125 degrees Celsius.
Even though Mars’ atmosphere is thin, the red dust is so light that winds can pick it up to create gigantic dust storms that can cover the entire planet! Just imagine a dust storm covering the entire Earth! Mars is only half the size of Earth though (just 6,780 kilometres across). Also, the wind can whip the dust up into mini-tornadoes called ‘dust devils’. Far from being a hazard, the dust devils actually help clean the dust off the solar panels of the two Mars rovers, Spirit and Opportunity!
Mars has two small moons, called Phobos (pronounced fo-boss) and Deimos (pronounced dee-moss). They are named after the Greek gods of fear and terror, so you have been warned! They are not that scary really. Astronomers think they used to be asteroids that were captured by Mars’ gravity. They are not round, but shaped like potatoes and are quite small: Phobos is 26.8 kilometres across and
Deimos is just 15 kilometres across. Phobos will also crash into Mars within a few hundred million years.
Click on each of the images below to find out more about that Solar System object!