Hello, I was wondering why is Mars red?
Mars is red because there is a lot of Iron Oxide in the soil. If you are interested in details on what Iron Oxide is then you can read http://en.wikipedia.org/wiki/Iron_oxide , but essentially it is an Iron and Oxygen compound more commonly known as rust. There is debate on why there is Iron Oxide in the soil. One idea is that this was made possible because there was water that eroded rocks revealing Iron underneath. Another idea is that the iron comes from meteorites. This is discussed in more detail here: http://www.slate.com/id/2093779/.
Image by NASA and STScI/AURA