This document summarizes information about various planets in our solar system. It provides brief descriptions of Mercury, Mars, Jupiter, and Saturn. Mercury is described as the closest planet to the Sun and the smallest planet. Mars is described as a cold planet despite its red color, due to it being full of iron oxide dust. Jupiter is described as the largest planet in the solar system and the fourth brightest object in the sky. Saturn is described as the ringed planet composed mostly of hydrogen and helium.