Mercury is the closest planet to the Sun in our solar system and the smallest, with a diameter of approximately 4,880 kilometers. Due to its proximity to the Sun, Mercury has one of the shortest orbits, completing a revolution around the Sun every 88 Earth days. The planet is named after the Roman messenger god because of its swift movement across the sky.

Mercury’s surface closely resembles the Moon’s, marked by numerous impact craters formed by collisions with meteoroids and comets over billions of years. Lacking a substantial atmosphere to retain heat, Mercury experiences one of the most extreme temperature variations in the solar system, ranging from scorching hot during the day (up to 430°C or 806°F) to freezing cold at night (-180°C or -292°F).

Despite its small size, Mercury has a magnetic field, which is unusual given its slow rotation—one Mercurian day equals 59 Earth days. This slow rotation, combined with its close proximity to the Sun, results in significant tidal effects in its gravitational interaction with the Sun. These effects have led to a unique orbital resonance, where Mercury rotates three times on its axis for every two revolutions around the Sun. This synchronization is a fascinating feature that distinguishes it from other planets in the solar system.