Magnetic Fields of Planets

Planets have a magnetic field that radiates from its core. These magnetic fields protect planets from the charged particles in the stellar wind and can also protect life on the surfaces of planets by blocking radiation.

A magnetic field is produced by a planet's inner and outer core. The varying pressures and temperatures in the inner and outer core produce convection currents, causing cool matter to sink and warm matter to rise. This whole process results in the production of electric currents, resulting in a magnetic field.

Planets that are close to stars are considered to be "tidally locked" because they are at the mercy of the gravitational pulls of the stars. Tidal locking is where the gravitational force exerted by an astronomical body on another is differential, which causes one side of the body to constantly face the other body. Tidally locked planets can have tidal heating produced by the gravitational pulls of stars, which can have an effect on the magnetic fields of these planets.

Scientists conducted research to determine if tidally locked planets do not have protective magnetic fields. What they found was that tidal heating can make a planet more efficient at dissipating heat, which cools the core of the planet and produces a magnetic field.

Source: http://scitechdaily.com/protective-magnetic-fields-increase-the-chance-for-life-on-earth-like-planets/