It's unclear why Earth is a magnet, but we think the movement of molten metal in its outer core & electric currents. The currents create a magnetic field via invisible lines of force flowing between Earth’s magnetic poles.
Geomagnetic poles aren't north and south poles.
Earth’s magnetic poles often move -> activity under Earth’s surface.
Shifting locations of geomagnetic poles = recorded in rocks formed when molten material (magma) wells up Earth’s crust and pours out as lava, before cooling and solidify, then strong magnetic particles in rock become magnetized by Earth’s magnetic field.
The particles line up along the lines of force in Earth’s field -> rocks keep Earth’s geomagnetic poles position.
Magnetic records = magnetic orientation recorded in rocks
Rock magnetic records formed at same time = show:
"Plate tectonics" theory says = rocky plates making up Earth’s hard shell are constantly moving -> plates on which the rocks solidified have moved since rocks recorded geomagnetic poles position.
Earth’s magnetic field doesn't move fast or reverse often -> can be useful to orient around.
Δ hundreds years, magnetic compass use Δ to navigate via Earth’s magnetic field.
A compass' magnetic needle lines up with Earth’s magnetic poles.
North end of a magnet points to North Magnetic Pole, holding a south magnetic charge.
Earth’s magnetic field dominates region called "magnetosphere" - wraps around Earth and its atmosphere.
Solar wind (charged particles of the sun) presses the magnetosphere against Earth on the side facing the sun and stretches it into a teardrop shape on the shadow side.
Magnetosphere protects Earth from most particles - some leak through and trapped. When particles of solar wind hit atoms of gas in upper atmosphere around geomagnetic poles & light displays called "auroras" - appear around places e.g. Alaska, Canada and Scandinavia, where are also called “Northern Lights.”
“Southern Lights” seen in Antarctica and New Zealand.
