Most destructive geomagnetic storm

The most destructive geomagnetic storm ever recorded was the "Great Geomagnetic Storm" of 13 March 1989, which was classified G5 (the most severe rating) on the space weather scale. The result of an abnormally strong solar wind, it caused large-scale disruption to the power grid in Canada and the USA, and changed the orbit of a satellite.

The solar wind is a stream of particles radiating from the sun into the solar system, and it is this phenomenon that is responsible for the northern and southern lights (aurora borealis, aurora australis). The Great Storm was caused by an eruption at a large sunspot – 54 times as big as the Earth – that propelled billions of tonnes of solar particles into space.

The power outages – caused by failures at the Hydro-Quebec systems – resulted in 6 million people being without electricity for nine hours. It also caused the Earth's atmosphere to expand, altering the orbit of a satellite.

The space weather scale is endorsed by NOAA (National Oceanic and Atmospheric Administration).