Mars is the third planet from the Sun, after Mercury and Venus. It is called "The Red Planet" because it looks red from Earth. It can often be seen low in the night sky at evening.
Mars was known to the antiquities; the Romans even named one of their gods — Mars, the god of war — after it. The Romans also knew about Jupiter and Saturn, but it was not until the 17th century that William Herschel discovered Uranus, and Neptune and Pluto took even longer.
Mars has two moons: Phobos and Deimos. Russian scientists in the 1950s posited that Phobos might be hollow, but these claims were discredited in the late 1960s.