What is the closest planet to the Sun?

Mercury is the closest planet to the Sun, located at an average distance of about 57.9 million kilometers (36 million miles). This proximity to the Sun has significant implications for its temperature and the characteristics of its surface, which experiences extreme temperature variations between day and night due to its thin atmosphere.

Mercury's orbit is highly elliptical compared to other planets, and it completes a full orbit around the Sun in just 88 Earth days, making it the fastest orbiting planet in our solar system. The planet's surface is heavily cratered, similar to the Moon, as it has not been significantly altered by geological activity over billions of years.

Understanding Mercury's position relates to the overall structure of our solar system, where the inner planets—Mercury, Venus, Earth, and Mars—are terrestrial and composed mostly of rock and metal, while the outer planets are gas giants. Mercury's unique characteristics highlight the diversity found among the planets in our solar system.