A significant geomagnetic storm caused by a very large X20 solar flare affected microchips and lead to the halt of Toronto’s stock market trading on August 16, 1989.

The solar flare was stronger than the X15 flare recorded in March of the same year. That flare caused extremely intense auroras and a geomagnetic storm that lead to the collapse of Hydro-Québec’s electricity transmission system.

Despite its lesser X15 potency, having a notable flare just five months before the August 1989 event provided some insight as to what was occurring. At the time of the March flare, some immediate concerns arose about a possible Cold War attack.

Since the two flares, power companies in North America, the UK, Northern Europe, and elsewhere have taken more care to evaluate the risks of geomagnetically induced currents and to develop mitigation strategies.

Both flares were part of the Solar Cycle 22, the 22nd solar cycle since 1755, when recording of solar sunspot activity began.

The sun follows the typical active star cycle where over the course of approximately 11 years energy goes from higher to lower levels, with the higher bringing solar flares to Earth.

Higher points and their associated solar flares were expected between 2012 and 2014; some 2012 doomsday believers made note of this. However, NASA advised that solar flares experienced during this time period would not be strong enough to physically destroy the Earth.

Since 1995, geomagnetic storms and solar flares have been monitored from the Solar and Heliospheric Observatory (SOHO), a joint-NASA-European Space Agency satellite.

According to SOHO data, powerful flares also erupted on April 2, 2001 (X20), October 28, 2003 (X17.2, see image below, taken by satellite), and November 4, 2003 (X28).



Source: NASA/SOHO Source: NASA/SOHO

NASA confirmed that a solar superstorm narrowly missed Earth in July 2012, which could have had a catastrophic effect on our technology. Significant data on the extreme storm cloud was collected because it did hit the STEREO-A spacecraft, a solar observatory in Earth orbit. NASA’s Solar Dynamics Observatory also reported a significant X8.2 solar flare in September 2017.

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For more moments in tech history, see this blog. EDN strives to be historically accurate with these postings. Should you see an error, please notify us.

Editor’s note: This article was originally posted on August 16, 2012, and edited on August 16, 2019.