Spots on the Sun

20 December 2001

For most Australians, summer means days spent by the beach and nights spent nursing our sunburn. Too much exposure to the sun can result in the appearance of 'sunspots' on our skin.

The Sun itself sometimes also has spots on its surface, which appear as irregular shapes with dark centres and lighter outer areas. Sunspots occur in active, stormy regions of the Sun where magnetic fields have become concentrated.

Sunspot activity can result in magnetic storms here on the Earth. Magnetic storms bring about disturbances in the Earth's upper atmosphere, which in turn can have hazardous effects on radio and satellite communications, radar, GPS, spacecraft, power-lines and pipelines.

The last large magnetic storm occurred on 24 November 2001 and prior to that the 6 November 2001.

Geoscience Australia maintains a network of geomagnetic observatories that measure changes in the Earth's magnetic field across Australia and in Antarctica, as well as providing magnetometer calibration and a compass capability.

NASA's spaceweather website gives daily updates on sunspot activity and advises on the potential threat from magnetic storms.

Nb: Never look directly at the Sun with the naked eye or with any optical instrument. You must be familiar with the safe observing methods before attempting to observe the Sun.

Topic contact: Last updated: October 4, 2013