http://science.nasa.gov/headlines/y2003/29dec_magneticfield.htm [Broken]Scientists have long known that the magnetic pole moves. James Ross located the pole for the first time in 1831 after an exhausting arctic journey during which his ship got stuck in the ice for four years. No one returned until the next century. In 1904, Roald Amundsen found the pole again and discovered that it had moved--at least 50 km since the days of Ross.
The "more to it" is that to be susceptible to picking up the same orientation as the then current magnetic poles, the rocks have to be hot enough for their magnetic domains to realign with the earth's field. Because of this, it should be clear why most of this rock with ancient compass orientations frozen into it is found around volcanos.Mr. dude said:The poles attract certain elements in the rock, which make them piont at where the pole is attracting them from. Theres probably more to this but just to give you the basic idea I posted.
But do they really? We know now that the Earth Magnetic field had collapsed about every 100,000 year in the current Brunhes Chron, the last ~800,000 years ago. If the migrating birds and other animals really relied on a biologic compass, how did they cope with that? It doesn't appear to have led to multiple extinctions.even animals that also rely on directional magnetism,
A quick Internet search with "Magnetic Field and Atmosphere" yielded several sites on the topic. There are different variables, the sun's magnetic field or "Interplanetary Magnetic Field" or "IMF," the solar winds, the density of a planet's atmosphere, etc.zoobyshoe said:I hadn't heard this. You wouldn't happen to have a link to a discussion/explanation of this would you?
http://spaceweather.com/glossary/imf.htmlEarth has a magnetic field, too. It forms a bubble around our planet called the magnetosphere, which deflects solar wind gusts. (Mars, which does not have a protective magnetosphere, has lost much of its atmosphere as a result of solar wind erosion.)
That site links to this site:SOS2008 said:A quick Internet search with "Magnetic Field and Atmosphere" yielded several sites on the topic. There are different variables, the sun's magnetic field or "Interplanetary Magnetic Field" or "IMF," the solar winds, the density of a planet's atmosphere, etc.