Roger Young, age 12, of Dallas., Texas, for his question:

Why are all planets round?

When you drop a dish it falls down. When a ripe apple breaks from the tree it falls down. A loose stone on a mountain peak slides down the slope. Landslides, avalanches, running water, rain, snow and hail all tumble down, down, down. Way back in the year 1666, a young man named Issac Newton figured out why all falling objects take a downward direction. He also figured that everything on the earth is drawn towards a point in the center of the globe on which we live.

The huge hugging power is, of course, the force of gravity. It works day and night pulling everything towards the center of the earth. It slowly levels the mountains. If the earth were square, the force of gravity would pull down the corners. It is gravity which makes the world round. And the force of gravity is in every object in the universe.

It is present in the planets and in the sun. These heavenly bodies are round, not square or oblong, because the force of gravity hugs everything to a central point.