Sunspots are temporary phenomena on the photosphere of the Sun that appear visibly as dark spots compared to surrounding regions. They are caused by intense magnetic activity, which inhibits convection by an effect comparable to the eddy current brake, forming areas of reduced surface temperature. They usually appear as pairs, with each sunspot having the opposite magnetic pole than the other.
Every three hours throughout the day, magnetic observers located all around our planet measure the biggest magnetic change that their instruments can record during that period. All the measured values are averaged all over the world and an index is obtained (the Kp index), telling researchers how disturbed the Earth’s magnetic field is on a [...]