Mars is a terrestrial planet, which means it is made up largely of rock. Elements that make up the rock include silicon and different types of metal.
Mars has a core that is very similar to the core of Earth. It is comprised of sulfur and iron which is enclosed in a mantle made of silicates. The whole planet is covered by a crust made of iron oxide and basalt and it is the iron oxide that gives the planet its red color.
Although there are similarities between the composition of Earth and Mars, there are also major differences. The core on Mars is solid and completely stationary while the core of Earth is molten and always moving. On Earth, the constant motion of the core protects the planet from solar radiation. Since the core of Mars never moves, the planet lacks this protection.
The crust on Mars is about 30 miles thick and consists mainly of volcanic basalt rock. This rock is covered by a fine layer of dust. The surface of Mars lacks tectonic plates and the crust is one piece. Although there are many volcanoes on Mars, there have been no volcanic eruptions for millions of years.
No liquid water exists on Mars because the planet's surface is too cold. The average temperature is -80 Fahrenheit although different areas of the planet can experience many temperature variations.