Final answer:
Auroras on giant planets are caused by the interaction of charged particles from the solar wind with the planet's magnetic fields, which channel these particles towards the poles where they excite atmospheric molecules, resulting in light emissions.
Step-by-step explanation:
The auroras observed on the giant planets are primarily caused by charged particles from the solar wind interacting with the planets' magnetic fields. Each of the giant planets, which include Jupiter, Saturn, Uranus, and Neptune, possesses a strong magnetic field generated by electric currents within their rapidly spinning interiors. These magnetic fields create vast magnetospheres, which are areas surrounding the planet where the planet's magnetic field is dominant. The charged particles are funnelled along these magnetic field lines towards the planet's poles. As they collide with atoms and molecules in the planet's atmosphere, they excite these particles, which then emit light, creating the spectacular light shows known as auroras.