The Earth’s magnetic field varies in strength depending on location, with regions near the poles having a stronger field. The magnetosphere affects the solar wind’s trajectory and the field’s total energy is large. The field’s orientation is reflected in cooled magma, which shows it flips every 250,000 years.
The earth’s magnetic field varies depending on your location on the earth’s surface. In regions close to the magnetic poles, such as Siberia, Canada and Antarctica, it can exceed 60 microtesla (0.6 gauss), while in regions farther away, such as South America and South Africa, it is about 30 microtesla (0.3 gauss ). Near the poles, the field strength decreases with the inverse square of the distance, while at greater distances, such as in outer space, it decreases with the cube of the distance. Where the prime meridian intersects with the equator, the field strength is approximately 31 microtesla.
The region where the Earth’s magnetic field lines extend into space is called the magnetosphere and affects the trajectories of the charged solar wind at distances greater than 10 Earth radii. The solar wind, ejected from the Sun in all directions at great speed, collides with the magnetosphere in a region called arc shock. Like gravity, magnetism has an infinite range, although it diminishes so rapidly with distance that its potency at distances far beyond 10 Earth radii is very low.
30-60 microtesla for the Earth’s magnetic field may not seem like a lot, but when you take into account the total volume of the field, its total energy is extremely large, much greater than any artificially generated magnetic field. To get a better idea of what a tesla is, a typical bar magnet has a field strength of 10 millitesla, a strong electromagnet 1 tesla, a strong laboratory magnet 10 tesla, and the surface area of a neutron star, approximately 100 megateslas.
The Earth’s magnetic field may not be as strong compared to localized magnetic fields, but it affects minerals all over the surface of the Earth. As magma seeps out of cracks in the oceans and cools, the orientation of the Earth’s magnetic field is reflected in the resulting structure of the cooled rock. By analyzing magma that hardened millions of years ago, scientists found that this field flips every 250,000 years or so.
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