Question: ok kara kardo, I want to know if you know the limit of the electromagnetic field of earth.

Freya Addison answered on 18 Nov 2019:

The Earth’s magnetic field changes a fair bit as it responds to its environment.
Typically the magnetic field extends to about 10 Earth radii from the centre of the Earth where it is facing the Sun and on the other side to 100s of Earth radii and stretches when interacting with the solar wind.
I recommend this article for a more detailed answer on the Earth’s Magnetic Field: https://web.ua.es/docivis/magnet/earths_magnetic_field2.html

The aurora borealis is caused by atmospheric particles interacting with charged particles from the solar wind which have travelled back along the magnetic field lines to the poles. (https://www.swpc.noaa.gov/phenomena/aurora)