Susanne Doris., age 11, of Staten Island, NY.., for her question:

How big is the planet mars?

If our world were a hollow ball., it could swallow six mars sized planets and still have room for dessert. The diameter of a planet is a line straight through the middle from pole to pole, and the diameter of mars is about 4200 miles. This is a little more than half the diameter of the earth.

On the scales, it would take almost 10 mars planets to equal the weight of the earth. So Mars is much smaller and lighter than the earth, and, therefore, its gravity is less. If your weight on earth is 100 pounds, you would weigh only 36 pounds on mars.