Mars is the fourth planet in the Solar System. It's known for its rich reddish surface, which is believed to come from thick iron based dust. Despite that color, it's actually on the colder side. A hot day on Mars is about 70 degrees Fahrenheit, while the all-time lowest temperature is recorded at -128 degrees Fahrenheit. It's not too different from Earth in size or day length. One day on Mars is about 24 hours and 40 minutes on Earth. A year on Mars is about 687 Earth days. When you go in order from closest to furthest from the Sun, Mars is the last planet with a solid surface in the Solar System. Our next planet is actually the biggest one!
[ADD PHOTOS OF MERCURY'S SURFACE, INTERIOR, MOONS?, AND MORE]