Geomagnetic storms are the cause of auroras. Geomagnetic storms that ignite auroras may occur more often during the months around the equinoxes. Proton auroras are usually observed at lower latitudes. The probe discovered auroras, but much weaker than those on Earth or other planets. Protons are also associated with auroras, both discrete and diffuse. Using the Hubble Space Telescope, auroras over Io, Europa and Ganymede have all been observed. The storm began on Earth with extremely intense auroras at the poles. Auroras have also been observed on Venus and Mars. X-ray emissions, originating from the particles associated with auroras, have also been detected. Thus the SKR is related to the auroras around the poles of the planet. The phenomenon is speculated by scientists to be a side-effect of strong auroras on Jupiter. The magnetic field in the upper atmosphere gives rise to the auroras. From here you can also see the auroras (northern lights). Similar sounds have also been reported during intense displays of Earth's auroras. During the winter, many international visitors go to Yellowknife to watch the auroras.