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What do scientists mean when they talk about Earth’s North and South Poles?

Magnetic Earth

The Magnetosphere

When you use a compass, the magnetized needle aligns itself with the Earth’s magnetic field and points to the North. That North is the Earth’s magnetic north, not it’s geographic north pole. The picture on the right shows the difference between the two.

Is NORTH really NORTH!

If you could draw a line from GCMS in Caldwell to the North Pole, that line would signify geographic north. If you then used a compass to point to the north and then drew a line, that would signify magnetic north. You would soon observe that those two lines are exactly the same. The angle of difference between the two lines is called the magnetic declination.

The diagram shows how much magnetic north has shifted in the last 180 years.

Caldwell to geographic north

Caldwell to magnetic north

Magnetic North is slightly to the West of Geographic North.

The circulation of the molten material in Earth’s core accounts for Earth’s

magnetic field.

Earth’s magnetic field also acts on ferromagnetic rocks, easily observed in samples from the ocean crust

Scientists observed that Earth’s magnetic field reverses itself every million years or so.

The Magnetosphere

What does the magnetosphere do?

• Field lines come out of the North and enter the South magnetic poles.

• Protects earth from solar wind – a blast of charged particles from the sun.

• Solar wind causes problems with satellites, power grids, UV radiation, and flight.

Aurora Borealis

“Northern Lights”

• High speed solar wind particles interact with atoms in our atmosphere.

• Electrons in those atoms give off light as they change energy levels.

• Northern Hemisphere = aurora borealis• Southern Hemisphere = aurora australis

What did you learn today?