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

Mercury is the closest planet to the Sun in our solar system. It is the first planet in the order of planets from the Sun. Let's explore in detail why Mercury is considered the closest planet to the Sun.

**1. Distance from the Sun:**
Mercury is located at an average distance of about 57.9 million kilometers (36 million miles) from the Sun. This makes it the closest planet to the Sun. The distance between Mercury and the Sun is about 0.39 astronomical units (AU), where 1 AU is the average distance between the Earth and the Sun.

**2. Size and Mass:**
Mercury is the smallest planet in our solar system, with a diameter of about 4,879 kilometers (3,032 miles). It is only slightly larger than Earth's Moon. In terms of mass, Mercury is also one of the smallest planets, with about 5.5% of Earth's mass.

**3. Orbit and Revolution:**
Mercury has the fastest orbit around the Sun compared to other planets. It completes one orbit around the Sun in about 88 Earth days. This rapid orbit is due to its close proximity to the Sun. Mercury also has the slowest rotation on its axis, taking about 59 Earth days to complete one rotation.

**4. Temperature Extremes:**
The proximity of Mercury to the Sun results in extreme temperatures on the planet's surface. During its daytime, the temperatures can reach up to 430 degrees Celsius (800 degrees Fahrenheit), making it the hottest planet in our solar system. However, at night, the temperatures can plummet to around -180 degrees Celsius (-290 degrees Fahrenheit) due to the lack of atmosphere to retain heat.

**5. Surface Features:**
Mercury's surface is characterized by numerous impact craters, similar to the Moon. It also has extensive plains and cliffs, including one of the biggest known impact basins called the Caloris Basin. The surface of Mercury is heavily cratered due to its lack of atmosphere to protect it from meteoroid impacts.

In conclusion, Mercury is considered the closest planet to the Sun due to its proximity, smaller size, faster orbit, and extreme temperature conditions. Its unique characteristics make it an interesting object of study for scientists and astronomers.