Merkuur
Merkuur is a celestial body within our solar system. It is the smallest planet and the innermost planet, orbiting closest to the Sun. Its surface is heavily cratered, bearing a strong resemblance to Earth's Moon. These craters are the result of countless impacts from asteroids and comets over billions of years. Merkuur has a very thin atmosphere, often referred to as an exosphere, which is composed of atoms blasted off its surface by solar wind and micrometeorite impacts. Due to its proximity to the Sun, Merkuur experiences extreme temperature variations between its day and night sides. Daytime temperatures can soar, while nighttime temperatures plummet to very cold levels. The planet has a very large iron core relative to its size, which is thought to be responsible for its surprisingly strong magnetic field, though it is much weaker than Earth's. Merkuur has no natural satellites or rings. Its rotation and orbit are in a peculiar resonance, completing three rotations for every two orbits around the Sun. Observations and data about Merkuur have been gathered by spacecraft, most notably by the Mariner 10 and MESSENGER missions, which have provided significant insights into its geology, composition, and environment.