Each planet is different. They are all different sizes โ Plutoโs the smallest, and Jupiterโs the biggest. They come in a variety of colors โ Mars is covered with rust, so it looks red; the methane (cold natural gas) in the atmosphere of Uranus makes it look blue; and Saturnโs colorful rings are made of icy rock. As far as we know now, Earth is the only planet in our solar system that is home to living things.