How does a boomerang return to the person who threw it?
asks Rajendra Singh, of Jaipur, India.

Baseballs don't. Footballs don't. Even frisbees don't. But boomerangs do--come back, that is.

If boomerangs were a new toy on the market--just invented--there would probably be a boomerang craze going on. Everyone would rush out and stand in long lines to be the first on the block to have one.

But in fact, boomerangs are very old. People were playing with the come-back toys thousands of years ago.

How did people invent boomerangs? Archeologists on their digs have found that early humans threw heavy wood weapons to kill animals for food and hides. (They also used the weapons in battles with other tribes). These weapons are called "throwing sticks," and they were made with a slight bend in the wood.

While experimenting with carving throwing sticks, someone--no one is sure where--probably made the first boomerang. Presto: A stick that acts like a carrier pigeon. And a toy that gives old meaning to the phrase "right back atcha."

Because that's what boomerangs are, and always were--toys. In old movies, boomerangs swished through the air, knocked down a bad guy or vicious animal, and spun obediently back. In real life, a boomerang that hits something plunks to the ground. And a boomerang wouldn't make a good weapon, anyway, because it must be made of very lightweight wood.

The feather-weight of a boomerang is one of the two things that make it different from a throwing stick. The other is its shape. Boomerangs are usually carved in v-shapes; wooden throwing weapons are straighter. A boomerang resembles an airplane, but without the body. A boomerang is all wing.

Boomerangs come back, according to physicists, for two main reasons: the shape of their "arms," or wings, and the way in which they're thrown.

Like an airplane wing, the underside of a boomerang arm is flat, and the top curved. The wing shape causes air rushing over the boomerang to lift it up. But boomerang wings are different. The curved top of one arm leans into the wind; on the other arm, the curve leans away.

If an airplane had such opposing wings, it would have a hard time flying straight. So does a boomerang--and that's the idea.

How it's thrown is also crucial. The boomerang is held vertical, its flat side pointing away from the thrower's body. With a snap of the wrist, it is tossed into the air. As it flies away, the boomerang is spinning end-over-end and traveling forward.

A right-handed boomerang turns left because of how wind rushes over its oddly-shaped spinning arms. As the boomerang travels forward, it's tugged back a bit each time an arm spins under. This creates pressure on top of the boomerang, and the boomerang gradually turns left. As it traces its big circle, it "lies down" like a rotating helicopter blade. The thrower holds out his hands, and the boomerang comes in for a soft landing.