Vanessa Peterson, age 10, of New Brunswick, New Jersey, for her question:

How long does sunlight take to reach the earth

The light from our starry sun whips through space at about 186,000 miles per second. It races across almost 93 million miles of space to reach our home planet. This fantastically fast trip takes about eight minutes and 20 seconds. So the sunbeam that just landed on your nose started out from the sun about 8 1/3 minutes ago. It traveled at its usual speed across the vast space between us and the sun. The air above the earth slowed it down very slightly, though not enough to make a second’s worth of difference.

The size of the sun is stupendous and its blazing light pours out in all directions, Only a tiny portion comes in our direction and falls on the earth. Our share amounts to about two parts in a billion parts of the total output. But it provides an enormous amount of energy. In one minute, it sheds on the earth enough energy to provide all the power we need in a year. Someday we may get our power from this free solar energy.