magnetosphere, its the magnetic lines of force generated by the moving magma inside the earth. It stops energized particles hitting the earth because a charged particle moving in a magnetic field creates a force perpendicular to the lines of force and the particle spirals down them to strike the earth at the poles. (the magnetic pole just happen to be near the rotational poles at this time) This all is the source of the northern (and southern) lights.
no
Mars has a magnetic field.
Surrounding a magnet with a magnetic shell can allow the magnetic field to move farther away from its source.
Most importantly to us, the earth has a permanent magnetic field.
The magnetic force on Earth is called Earth's magnetic field or also the geomagnetic field.
Planet Earth
Jupiter
liquid core
Uniform magnetic field depends on the position of its surrounding. A non uniform magnetic field changes its position from one place to another.
To start if we didnt have a magnetic field we would be fried by the suns radiation. The northern lights are evidence that we have a magnetic field surrounding earth.
A magnetic Field
Magnetic field