A magnetic field is an invisible force that surrounds a magnet or electric current and exerts a force on other magnets or moving charges. It is represented by lines of force that extend from the north pole of a magnet to the south pole.
Earth's magnetic field is generated by the movement of molten iron in its outer core. The rotation of the Earth and convection currents in the liquid iron create an electric current, which in turn creates a magnetic field.
The strength of Earth's magnetic field varies depending on location, but on average, it is around 25-65 microteslas (µT) at the surface. At the poles, it can be as high as 60-70 µT.
The strength of Earth's magnetic field is measured using a device called a magnetometer. This instrument detects the direction and strength of the magnetic field and can be used to create maps of the field over different areas.
Yes, the strength of Earth's magnetic field is not constant and has been fluctuating over time. In fact, it has been weakening over the past few centuries and could potentially reverse in the future, where the north and south poles switch places.