Mars' outer crust is 6 to 30 miles (10 to 50 km) thick and is composed mainly of iron, magnesium, aluminum, calcium and potassium, according to NASA. Below that is a rocky mantle that's 770 to ...

On a flyby of Mars, the European Space Agency (ESA) captured a rare photo of its second moon - but what do we know about it? It's called Deimos, and is much smaller and more mysterious than Phobos ...