Earth’s Magnetic Field Text 5.6 pp 165-168 The Magnetosphere And The Van Allen Belts

Magnetic Fields and Field Lines A magnetic field is generated by a moving electric charge, such as in a magnet or an electric current. It “pushes” on moving charged particles.

Magnetic field lines show which direction a charged particle is pushed by a magnetic field. You can use a compass to show the direction of the lines.

The Origin of Earth’s Magnetic Field The spinning of the metallic Inner Core and convection currents in the metallic Outer Core create a magnetic field around the Earth.

The magnetic poles are close to - but not exactly the same - as the geographic poles of Earth.

The earth’s magnetic field is not actually generated by a magnet The earth’s magnetic field is not actually generated by a magnet. The earth’s outer liquid core is mostly made up of iron that convects very rapidly, acting as a “dynamo” that generates a magnetic field.

The strength of the field is directly related to: The metal mass of the inner core. How fast it spins.

Are Earth’s Magnetic Poles Stable? No! They wander over the Earth’s surface. Since 1945, they have moved at a rate of almost 12 km a year.

About every 500,000 years Earth's magnetic field gets progressively weaker, vanishes, then reappears with the magnetic North and South poles reversed.

The Magnetosphere and the Van Allen Belts The magnetic field traps the charged particles of the ionosphere, pushing them into the magnetosphere, which stretches out two or three times Earth’s Radius!

They form two donut shaped belts called the inner and outer Van Allen Belts. Particles in the belts are dangerous to spacecraft and astronauts, as they can pierce through their surfaces.

Protection and The Aurora The magnetic field protects us by channeling super-fast, high energy- charged particles from the Sun away from the Earth. They flow around the field….

The Aurora This causes electrons to flow along the field lines to the poles, where they rain down - energizing the molecules of the atmosphere and making them glow.

The colors of the aurora depend upon the gases interacting with the solar particles streaming from the Sun.

We are having a particularly beautiful and beautiful aurora season this year, as we head into a phase of active solar activity.

This photo of aurora was taken on February 18, 2012, in Nebraska!