Which planet is known as the Red Planet?

Mars looks red because its surface is genuinely rusty. The soil is rich in iron, and over billions of years that iron reacted with oxygen to form iron oxide, the same compound that reddens a neglected garden tool. Fine dust of that oxide covers the planet and is lifted by wind into storms that can wrap the whole globe, giving even the sky a butterscotch tint. The colour is obvious enough to the naked eye that ancient observers noticed it, which is why so many cultures associated the planet with blood and war and why the Roman name for the god of war stuck. Mars has held onto its rust partly because it lost most of its atmosphere: with a thin, dry air and no oceans or plate tectonics to bury and recycle the surface, the oxidised layer simply stays where it is rather than being weathered away.

Mars has two small, irregular moons, Phobos and Deimos, whose names mean fear and dread.