**The Planet closest to the Sun: Mercury**

Mercury is the closest planet to the Sun in our solar system. It is named after the ancient Roman messenger of the gods because it moves across the sky faster than any other planet. Let's explore some key features and facts about Mercury.

**1. Distance from the Sun:**
Mercury orbits the Sun at an average distance of about 57.9 million kilometers (36 million miles). Due to its proximity to the Sun, Mercury experiences extreme temperature variations, ranging from -173°C (-280°F) to 427°C (800°F) on its surface.

**2. Size and Composition:**
Mercury is the smallest planet in the solar system, with a diameter of approximately 4,879 kilometers (3,032 miles). It is composed primarily of rock and metal, with a thin atmosphere and no moons. Its surface is covered in craters, similar to the Moon.

**3. Orbit and Rotation:**
Mercury's orbit is highly elliptical, meaning it is elongated rather than circular. It takes about 88 Earth days to complete one orbit around the Sun. Interestingly, Mercury also has a slow rotation, with one day on Mercury lasting about 59 Earth days. This means a single day on Mercury is longer than its year!

**4. Lack of Atmosphere:**
Unlike some other planets, Mercury has a very thin and virtually non-existent atmosphere. This lack of atmosphere allows extreme temperature differences between its sunlit and shadowed regions.

**5. Missions to Mercury:**
NASA's Mariner 10 mission in the 1970s provided the first close-up images of Mercury, revealing its surface features and characteristics. More recently, the European Space Agency's BepiColombo mission was launched in 2018 to further study and explore Mercury.

**Conclusion:**
Mercury, being the closest planet to the Sun, has unique characteristics such as extreme temperature variations, a lack of atmosphere, and a highly elliptical orbit. Its proximity to the Sun makes it a fascinating subject for scientific exploration and study.