Compass

Animals Use Chemical Compasses, Study Says

Publication: National Geographic News   Date: April 30, 2008   View Article

The idea that some animals navigate by “seeing” Earth’s magnetic field has been shown to be feasible in laboratory tests, a new study says.

First proposed about 30 years ago, the theory suggests that sunlight absorbed by molecules in the eyes of animals such as birds and bats triggers a chemical reaction.

Birds Can “See” Earth’s Magnetic Field

Publication: National Geographic News   Date: September 27, 2007   View Article

To find north, humans look to a compass. But birds may just need to open their eyes, a new study says.

Scientists already suspected birds’ eyes contain molecules that are thought to sense Earth’s magnetic field. In a new study, German researchers found that these molecules are linked to an area of the brain known to process visual information.

Why Does Earth’s Magnetic Field Flip?

Publication: National Geographic News   Date: September 27, 2004   View Article

Earth’s magnetic field has flipped many times over the last billion years, according to the geologic record. But only in the past decade have scientists developed and evolved a computer model to demonstrate how these reversals occur.

“We can see reversals in the rocks, but they don’t tell us how it happens,” said Gary Glatzmaier, an earth scientist and magnetic field expert at the University of California, Santa Cruz.

Earth’s Magnetic Field Is Fading

Publication: National Geographic News   Date: September 9, 2004   View Article

Earth’s magnetic field is fading. Today it is about 10 percent weaker than it was when German mathematician Carl Friedrich Gauss started keeping tabs on it in 1845, scientists say.

If the trend continues, the field may collapse altogether and then reverse. Compasses would point south instead of north.

Migrating Birds Reset “Compasses” at Sunset, Study Says

Publication: National Geographic News   Date: April 15, 2004   View Article

Sunset is more than a thing of beauty for Swainson’s thrushes and gray-cheeked thrushes. It keeps them on course when migrating between their winter and summer homes, according to an international team of scientists.

The finding sheds further light on a question that has vexed scientists for years: How do birds navigate between nesting areas separated by thousands of miles with pinpoint accuracy?

© 2008-2010 Collected Writings By John Roach