In recent days, the Sun has experienced several powerful eruptions that have sent large amounts of matter from the Sun’s corona (the hot gas surrounding the star) toward Earth. According to the US National Oceanic and Atmospheric Administration (NOAA), magnetic storms have been and will be an observable effect directly on our planet.
Eruptions on the Sun started already on Monday. A pulse of strong ultraviolet radiation from one of them hit Earth on Tuesday and was felt in the South Pacific region, where sailors and amateur radio operators could experience a loss of signal on frequencies below 20 MHz for about one hour, according to SpaceWeather.com.
Earth was expected to feel further effects on Thursday and Friday.
NOAA’s original forecast indicated that geomagnetic storms of G1 intensity, the lowest of a total of five levels, were expected on Thursday, November 30. On Friday, December 1, the storms were expected to reach the G2 level, or “moderate.”
Such a strong geomagnetic storm can, in addition to moderately serious radio signal outages, also cause problems with high-voltage power lines, navigation systems, and displacement of the aurora borealis, for example, over New York City.
However, on Wednesday, NOAA changed its forecast for Friday, saying an even stronger geomagnetic storm reaching the G3 level, which NOAA describes as “strong” on its scale, is likely on Friday. In this case, the aurora borealis can move even further from the poles and all the other problems mentioned for the G2 level can be a little more pronounced.
The reason for the change in the forecast, according to SpaceWeather.com, is an estimate that a so-called “cannibal” effect will occur. This term refers to geomagnetic storms that cause ejections of matter from the Sun, which are so fast that they absorb material from previous ejections on their way to Earth and thus strike with even greater force. Different eruptions eject matter at different speeds, and it can thus travel to Earth in less than a day, but even several days.
According to NOAA, an average of 200 G3 geomagnetic storms occur per solar cycle, which lasts 11 years.