How Come?

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.

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What causes quicksand, and where is it found? asks Edward McClarty, of San Francisco.

Unless you’re on Gilligan’s Island, roiling pits of dangerous quicksand aren’t found around every bend in the trail. There are a lot of myths about quicksand, among them:

Quicksand sucks you down like a vacuum cleaner. In fact, quicksand doesn’t pull you down any more than a swimming pool does. Quicksand is more buoyant than water, so it’s actually easier to float in quicksand than in a swimming pool.

Quicksand is a bottomless pit. Most patches of quicksand are a few inches to a few feet deep.

Quicksand is always made of sand. In addition to sand, clay, swamps, and silt can all become what scientists call “quick.”

By now you might have guessed that what we call “quicksand” is more of a phenomenon than a thing. The phenomenon is “quickness,” the way water flowing through sand, clay, or other material lifts and separates its small grains.

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Why does the moon look gigantic rising on the horizon but not nearly so large overhead? asks Jerry Hostetler, of Phoenix, AZ.

Have you ever been riding in a car in the evening and noticed something huge and yellow behind the trees and buildings in the east–and then realized it was the Moon? Especially in the fall, a pumpkin-colored harvest moon, looming up over the horizon, looks enormous and even spooky. It’s not hard to imagine a broomstick-riding witch flying across.

But picture this Halloween scene when the moon is high in the sky, small and white, and it’s just not the same.

Scientists say that the horizon Moon appears up to twice as big as the overhead Moon to most of us. People have been arguing over why for more than a thousand years. Astronomers, psychologists, and nonscientists all have their theories. In 1989, researchers even published a book of such explanations, called “The Moon Illusion.”

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Which came first, the chicken or the egg? asks Jessica Bolz, a student in Melville, NY.Chicken or egg? Like a hall of mirrors at the carnival, each attempt at an answer just leads to another question. If the chicken came first, then didn’t it hatch from an egg? And if the egg came first, wasn’t it laid by a chicken? It’s one of those questions that seem unanswerable.

Scientists agree on where chickens came from: In a sense, human beings invented them, just like they invented cows and pigs and other domesticated animals on Old MacDonald’s Farm.

If chickens were interested in tracing their family trees, they would need to bone up on some DNA research done in Japan. Every chicken that ever lived can trace its ancestors, say researchers, to a particular subspecies of Red Jungle Fowl in Thailand.

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How come it is still light for an hour after the sun sets? asks P. Ramana Mohan, of India.Twilight time: a time of purple clouds, deepening shadows, a fading glow in the sky. Still light enough to play outside, but getting harder and harder to read without a lamp. As a song made popular by the group The Platters in 1958 goes, “Heavenly shades of night are falling; it’s twilight time.”

Twilight usually refers to the time just after the sun sets in the evening. But it also can mean the time just before the sun rises in the morning. During twilight, although the sun is hidden below the horizon, the sky is still aglow with light, gradually dimming (after sunset) or intensifying (before sunrise).

During twilight, the light for our evening activities comes courtesy of the upper atmosphere.

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Why do leaves change color in the fall? asks Patricia Brown, of New York City.Autumn’s cool days are trimmed with deep blue skies and golden light, and brilliant leaves of yellow, orange and red. Leaves changing color in the fall are a tree’s way of preparing for long winter, rather like we put up storm windows and pull warm clothes and blankets out of storage.

In summer, the leaves on trees like pin oaks and sugar maples are green because they are chock-full of the green pigment chlorophyll.

Trees need sunlight to produce chlorophyll. In turn, chlorophyll uses sunlight’s energy to split water (H2O) into hydrogen and oxygen. Meanwhile, leaves also absorb carbon dioxide gas from the air. The end products of leaf chemistry: carbohydrates (homemade plant food for the tree), and oxygen, released into the air (the gas we need to breathe). The whole process is called photosynthesis.

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