Explanation

The second smallest planet is Mars,

It is about half the size of the Earth with a 2,106-mile radius. 

Mars is sometimes called the Red Planet.

It's red because of rusty iron in the ground.

Number of moons on Mars: 2

Additional information:

The planets in order of size, listed from biggest to smallest:

1. Jupiter: 43,441-mile radius.
2. Saturn: 36,184-mile radius.
3. Uranus: 15,759-mile radius.
4. Neptune: 15,299-mile radius.
5. Earth: 3,959-mile radius.
6. Venus: 3,760-mile radius.
7. Mars: 2,106-mile radius.
8. Mercury: 1,516-mile radius