Maris Valainis, age 10, of Indianapolis, Indiana, for her question:

How big is the Solar System?

The shape of the Solar System is fairly flat and almost round. The shining sun is almost at the center. The nine planets orbit around it, one outside the other. It seems logical to measure the size of the Solar System from the orbit of the farthest planet, which is little Pluto. The average distance between Pluto and the sun is about 3,670 million miles. From side to side, clear across the orbit of Pluto, the Solar System is about 7,340 million miles wide.

The speed of light is almost 700 million miles per hour. At this speed we could zoom clear across the Solar System in much less than a day. At 1,000 miles per hour, the trip would take almost 100 years. We can picture the huge system better if we scale down its size. If the giant sun were a beach ball, the entire Solar System would be a little more than three miles wide