Magnetosphere
Topic: Origin and Evolution of the Earth and the Solar System · NCERT: Beyond NCERT
Meaning
The magnetosphere is the region around the Earth controlled by the Earth's magnetic field. The field comes from the geodynamo, which is moving liquid iron in the outer core. The magnetosphere shields the planet from the solar wind and cosmic rays. The solar wind squashes it on the side facing the Sun and stretches it into a long tail on the night side. It also traps charged particles in two rings called the Van Allen belts. This shield helped the Earth keep its atmosphere and its water.
Example
Mars lost its global magnetic field, and after that it lost most of its air to space. The Earth kept its magnetic shield, and so it kept its air and oceans.
Don't confuse with
- Ozone layer: a layer of gas in the atmosphere that absorbs the Sun's ultraviolet rays. The magnetosphere is a magnetic field that turns away charged particles. It reaches far beyond the atmosphere.