Balog, age 9, of Gary, Indiana, for his question:

How close does Mars come to the earth?

In 1956, the distance between Mars and the earth dwindled to about 35 million miles. This is the closest the two planets ever come to each other. Astronomers call this event a favorable opposition. And after each favorable opposition we have to wait 15 years or 17 years for the next one. Meantime the two planets are whirling around their different orbits at different speeds. The earth has the smaller, inside orbit. The wider orbit of Mars is way outside us. As we go around the sun, the earth on the inside lane is always catching up and passing Mars in the outer lane.

Every year, the two planets happen to be on the same side of the sun at the same time. This is when you would expect them to come closest. But the orbit of Mars is oval shaped and ours is rounder. On one side the distance between the orbits is 60 million miles. On the other side it is only 35 million miles. When the two planets come closest, they are on the same side of the sun    and just where the distance between their orbits is the shortest.