Mercury is the closest planet to the sun. The next closest planet is Venus, followed by Earth.
Being closest to the sun, Mercury has the shortest orbit of approximately 88 days long. Unlike some other planets, Mercury has no moons or rings. Due to having a near non-existent atmosphere, the surface temperature of Mercury varies widely. The surface can reach up to a temperature of 800 degrees Fahrenheit during the day, and as low as -280 degrees at night. Every two full orbits around the sun, Mercury revolves exactly three times. This means that the days on Mercury are extremely long compared to days on Earth.