Here's why:
* AU (Astronomical Unit): An AU is the average distance between the Earth and the Sun, about 93 million miles (150 million kilometers).
* Mercury's Orbit: Mercury orbits the Sun at an average distance of 0.39 AU. This means it's significantly closer to the Sun than Earth.
The other planets in our solar system are all farther away than 1 AU:
* Venus: 0.72 AU
* Earth: 1 AU
* Mars: 1.52 AU
* Jupiter: 5.20 AU
* Saturn: 9.58 AU
* Uranus: 19.22 AU
* Neptune: 30.06 AU
