which planet is closest to the sun?
The planet that is closest to the sun is Mercury. Mercury is the smallest planet in our solar system and is located closest to the sun. Because of its proximity to the sun, temperatures on Mercury can reach up to 800 degrees Fahrenheit in the day and drop to -290 degrees Fahrenheit at night. Despite its small size, Mercury has a relatively large iron core and a thin atmosphere mainly made up of helium and sodium.