Q) Do plants go potty?
Haynes Werner, W. Glacier, MT (Age 4)
A) Plants and people work in very different ways, so comparing them is a bad ideabut for an eager sprout like you we'll make an exception. One big difference involves how they take in nutrition. As Gary Watson, a botanist at Chicago's Morton Arboretum, puts it, "Plants build up, and people break down." In other words, humans get their nutrients by gobbling food, with help from a complex digestive system that breaks the grub down into substances the body can use. Plants make their own food, from a dozen basic building blocks that they borrow from the environment. Since people are less discriminating about their intake than plants are, most of what they eat must be disposed of as waste. A plant takes only what it needs to convert carbon dioxide and water into victuals, using energy from the sun, so there is no waste, only extra oxygen plus some sugar water that seeps out of its roots. Even this is put to good use: It's food to the fungi and bacteria in the soil. "I wouldn't call that waste," says Watson. "I'd call it sharing."
Q) Is it possible to see the North Star and the Southern Cross from the same spot?
Kirk Mason, Rio Rancho, NM
A) For those who snoozed through Astronomy 101, the North Star, a.k.a. Polaris, which sits above the north celestial pole, and the Southern Cross, a crucifix-shaped constellation that points to the North Star's counterpart, Sigma Octanis, have been crucial navigational aids through the ages. Yes, you can see them at the same timeyou could even build a nice vacation around it. "Try Jamaica from March till June," says Geoff Chester, an astronomer at the U.S. Naval Observatory, in Washington, D.C. During those months, Westerners can see the Southern Cross up to about 22 degrees northe.g., the upper Caribbean. The North Star is visible year-round if you're situated more than five degrees north of the equator. South of that, it's usually too close to the horizon to be seena fact that European sailors learned the hard way when sailing the planet's midsection.
Q) What's the highest mountain that ever existed on earth?
Leigh Ann Roberts, Nashville, TN
A) No one's sure, but according to Chuck Barnes, geology professor emeritus at Northern Arizona University, it's doubtful there's ever been a mountain much higher than ol' 29,035-foot Everest. Blame it on Archimedes' Principle: Mountains "float" on the earth's slightly denser mantle just as a ship floats on water; add more height (meaning weight) and the mountain will sink farther into the mantle. On smaller planets, with less gravity, mountains are able to get tallerthus, a Sherpa on Mars would have to climb 88,000 vertical feet to summit Olympus Mons, the highest mountain in the solar system. Still, Barnes says, it's reasonable to think that our planet once hosted other mountains in the Everest ballpark: Evidence strongly suggests that 200 million years ago, the Appalachians were similar in size to today's Himalayas.
Q) Why do loons have red eyes?
Susanna Weber, Stevens Point, WI
A) We can rule out hangovers, but after that, things get sketchy. Loons, like a dozen other U.S. species, are born with gray eyes that turn red in their second year. It's not clear why, but David Evers, a biologist at the University of Southern Maine, says some theories hold more water than others. Bright colors can help female birds pick out sexier males, but it's size and plumage that count to a loon, not the eyes. More plausible is that red eyes filter out the green and blue light that dominates in deep lakes, making the yellow perch that loons prey on stand out better. But that theory's iffy, too: Loons spend their winters in salt water, hunting different-colored fish. It may be that loons have red eyes not because they're useful but because they used to be usefulin other words, maybe they're just evolutionary remnants, like your tonsils, whose original function has been lost.
Q) Do plants go potty?