StarGateWars Forums

...globally the magnetic field has weakened 10% since the 19th century. When this was mentioned by researchers at a recent meeting of the American Geophysical Union, many newspapers carried the story. A typical headline: "Is Earth's magnetic field collapsing?"
...
Probably not. As remarkable as these changes sound, "they're mild compared to what Earth's magnetic field has done in the past," says University of California professor Gary Glatzmaier.

Sometimes the field completely flips. The north and the south poles swap places. Such reversals, recorded in the magnetism of ancient rocks, are unpredictable. They come at irregular intervals averaging about 300,000 years; the last one was 780,000 years ago. Are we overdue for another? No one knows.
...
Earth's present-day magnetic field is, in fact, much stronger than normal. The dipole moment, a measure of the intensity of the magnetic field, is now 8 × 1022 amps × m2. That's twice the million-year average of 4× 1022 amps × m2.
...
Using the equations of magnetohydrodynamics, a branch of physics dealing with conducting fluids and magnetic fields, Glatzmaier and colleague Paul Roberts have created a supercomputer model of Earth's interior. Their software heats the inner core, stirs the metallic ocean above it, then calculates the resulting magnetic field. They run their code for hundreds of thousands of simulated years and watch what happens.

What they see mimics the real Earth: The magnetic field waxes and wanes, poles drift and, occasionally, flip. Change is normal, they've learned.

[KMA]Avenger wrote:An eye opening article!
http://www.nasa.gov/vision/earth/lookin ... field.html

Baxter wrote:from http://science.nasa.gov/science-news/sc ... eticfield/