The Earth's Magnetic Field - A mystery

The earth's magnetic field is a strange phenomenon which is not clearly understood by science. It extends from the Earth's inner core to where it meets the solar wind, a stream of energetic particles emanating from the Sun

We know the source of the magnetic field lies within the Earth's interior of which we have only limited knowledge of the composition of the materials and their
earth core
physical conditions.

The source of the magnetic field appears to be currents and magnetic fields mixed in the turbulent motion of hot conducting fluids, or semi-solids, influenced by the rotation of the planet and this produces a dynamo effect of circulating electric current.

Although the details of the dynamo effect are not known in detail, the rotation of the Earth plays a part in generating the currents which are presumed to be the source of the magnetic field. Mariner 2 found that Venus does not have such a magnetic field although its core iron content must be similar to that of the Earth. Venus's rotation period of 243 Earth days is just too slow to produce the dynamo effect.

These solar winds would be very damaging but the Earth's magnetic field shields us, deflected like water around the bow of a ship.

The magnetosphere

The solar wind is a stream of ionized gases that blows outward from the Sun at around 400 km/second. The intensity of solar winds varies with the amount of surface activity on the Sun.

The imaginary surface at which the solar wind is first deflected is called the bow shock and the area behind and surrounding the Earth is termed the magnetosphere.
solar winds


it represents a region of space dominated by the Earth's magnetic field in the sense that it largely prevents the solar wind from entering. However, some high energy charged particles from the solar wind leak into the magnetosphere and are the source of the charged particles trapped in the Van Allen belts. Interaction of the terrestrial magnetic field with particles from the solar wind sets up the conditions for the aurora phenomena near the poles.