Which is the smallest planet in our solar system?

The smallest planet in our solar system is Mercury. It has a diameter of about 4,880 kilometers (3,032 miles), making it even smaller than some of the moons that orbit other planets.

Mercury's small size can be attributed to its close proximity to the Sun. Its surface is heavily cratered, resembling that of Earth's Moon, which suggests that it has not experienced significant geological activity to reshape it over billions of years. This solidifies its status as the smallest planetary body officially recognized in our solar system as a planet, contrasting with the larger sizes of Mars, Venus, and Earth, which are all notably bigger with diameters exceeding 6,000 kilometers. Mercury’s inability to hold onto a thick atmosphere, partly due to its small size and proximity to the Sun, also contributes to its distinctive characteristics compared to the other planets in our solar system.