The document summarizes key facts about the inner planets Mercury, Venus, Earth, and Mars. It describes each planet's diameter, average temperature, mass, distance from the sun, and main components. Mercury is the closest planet to the sun and has an average temperature of 45 degrees. Venus is similar in size to Earth but has a dense carbon dioxide atmosphere. Earth's mass is 13,200,000,000,000,000,000,000,000 pounds and it is comprised primarily of iron, oxygen, silicon and magnesium. Mars is around half the size of Earth and has only a thin carbon dioxide atmosphere.
