US space agency NASA warns that for millions of GPS users, the spectacular phenomena could become an electronic nightmare as satellites fail due to the cosmic bombardment.

With the beginning of a new 11-year cosmic cycle, the number of sunspots will increase along with the possibility of a solar super storm. NASA data show the peak of solar activity will be in 2015.

The so-called space weather is as difficult to predict as the climate on Earth and it has the potential to affect our climate.

In January, NASA sent a space probe to research the solar cycle and space weather. It reported: ''Space weather can affect polar aircraft flights, disable satellites, cause power-grid failures and disrupt global positioning system, television and telecommunications signals.''

Dr Paul Francis, of the ANU College of Physical and Mathematical Sciences, said NASA's warning should be heeded.

Computer- and satellite-dependent economies could be in trouble when the Earth is hit by a solar flare.

''Small solar storms can damage satellites but a big solar storm has the potential to knock out most power grids on Earth,'' Dr Francis said. ''These solar storms last only minutes but the damage they cause could last for months and years.''

The largest event of this sort took place in 1859 and caused the failure of telegraph systems around the globe.

In 1998, a sun storm crashed the ''fault-tolerant'' computer of the Toronto Stock Exchange causing mayhem on the trading floor for three hours.

Sunspots were discovered by Galileo Galilei in 1610.