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Ancient whirlpools, skinny Venus, bird brains

Q: Can ships really get pulled down by the whirlpool (named, Charybdis) that Ulysses struggled with? Or was that just a myth? William, Albuquerque, New Mexico

A: The whirlpool, Charybdis, may have existed but it didn’t then nor now suck ships down.

The myth paints a different picture:

"[Charybdis] was a gulf, nearly on a level with the water. Thrice each day the water rushed into a frightful chasm, and thrice was disgorged. Any vessel coming near the whirlpool when the tide was rushing in must inevitably be ingulfed; not Neptune himself could save it." From Bullfinch’s Mythology.

But whirlpools are almost never as bad as their reputation. Powerful whirlpools have killed seafarers and devoured an occasional small boat — but not Ulysses’ 20-oar galley nor modern ships.

Here, at the Strait of Messina, Ulysses may have narrowly escaped the whirlpool Charybdis only to encounter the monster rock, Scylla. [NASA]

Further Surfing:

Science Museum, Chili: large whirlpool exhibit.

University of Toronto: In the wake of the Odyssey — actual locations

Skinny Venus

Q: Is there ever a "full Venus" and how bright would it be? When we look through our telescope, we always see a crescent Venus. My son, Teddy, says the sun casts a shadow that causes Venus’ phases. Is he right? (Marilyn, Albuquerque, New Mexico)

A: Teddy is right. The phases of Venus are much like the phases of the Moon. The Sun illuminates half the planet. We see portions of the illuminated half from various viewpoints as both Earth and Venus orbit the Sun. Those different views cause the phases of Venus.

Venus and Earth orbiting the Sun, showing four of the phases of Venus.  [April Holladay]

Yes, there is a Full Venus but we, on Earth, can never see it because it occurs when the Venus is opposite the Sun from us and the Sun blocks it from view. Actually, even an almost Full Venus is not so bright (from here) because, when Venus is full, it is also farthest from us and therefore dimmest.

As Venus sweeps around the Sun towards us, the planet appears bigger and brighter like the headlights of an approaching car. On its way, Venus gradually changes from "Full" to "Half", and finally to "Crescent" when close to Earth. Even a fairly skinny Crescent Venus (more than a few percent) appears brighter because it is so much closer than a Full Venus.

When Venus is closest to Earth, Venus is between us and the Sun and therefore "New", dark, and unseen.

By the way, just as the Moon eclipses the Sun, so does Venus. This is called the "transit" of Venus. It only happens about twice a century. We can see this rare event soon — on June 8^th. Then Venus cruises across the Sun like a moving black dot. More about the transit coming in next week’s column.

Further Surfing:

University of Virginia: Phases of Venus by Michael Fowler — a cool movie that shows how the Sun creates the phases and how they look as Venus approaches and recedes from Earth. Click the green triangle at the bottom of the screen to start the movie.

Royal Observatory Greenwich: Venus

Bird brains

Q: I heard that pigeons are rated number 3 on the list of the smartest birds. Is this true? What is a pigeons IQ? Where are they on the list of smart birds? (Spencer, Vancouver, Washington)

A: They don’t make the number 3 grade but they can do smart things.

A wild rock dove. Pigeons are semi-domesticated descendants of the rock dove. [U.S. Fish & Wildlife Service]

Pigeons can peck keys in a certain pattern, can distinguish a symmetrical object from a non-symmetrical one, and even pick out a series with an oddball in it. For example, they can select a screw from a bunch of aspirins. But so can other cage birds, like canaries.

More impressive, a pigeon distinguished between a Picasso and a Monet painting in experiments at Cardiff University in Britain. The pigeon may have held an idea (Picasso’s style) in its head to make the distinction.

Furthermore, pigeons can solve problems (like chimpanzees). Pigeons learned to peck at a banana placed directly above them. Separately, they learned to push a box along the ground. Then experimenters hung the banana too high for the pigeons to reach and also stuck a box in the room some distance away. The pigeons pushed the box to the banana, hopped on it, and pecked at the banana.

"I wouldn’t give pigeons a top mark for smarts," says Charles Walcott, neurobiology professor and faculty dean at Cornell University. They are "phenomenally good", however, at spotting a human face in a picture. Walcott recalls a study by Richard Hernstein at Harvard. The pigeon kept insisting that a slide contained a human face. None of the investigators could see it — just a house with a hedge. "Finally, somebody spotted a small child looking out the hedge!"

Further Reading:

PBS: Bird brains

Ehrlich, Paul R., D.S. Dobkin, and D. Wheye. The Birder’s Handbook. New York: Simon & Schuster, Inc. 1988.

(Answered May 28, 2004)