Which planet is closest to the sun?

Mercury is the closest planet to the Sun in our solar system. It orbits the Sun at a distance of approximately 57.91 million kilometers (36 million miles) on average. One of the key characteristics of Mercury is its extremely rapid orbital period; it takes only about 88 Earth days to complete one orbit around the Sun. This proximity to the Sun leads to significant temperature fluctuations on the planet, contributing to its unique surface conditions.

In contrast to the other options, Venus, Earth, and Mars are all farther from the Sun than Mercury. Venus, while it is often called Earth's "sister planet" due to its similar size and composition, is the second planet from the Sun. Earth, our home planet, is the third, and Mars follows as the fourth planet. Therefore, Mercury’s position in terms of distance from the Sun solidifies it as the closest planet in our solar system.