An eruption of energy from the sun is possibly due to sideswipe Earth on Wednesday, marking the third time in a week our planet has narrowly escaped a direct hit.
The solar eruption, known as a coronal mass ejection or CME, is due to make a glancing blow to Earth on March 23 according to SpaceWeather, which cited forecasts by the U.S. National Oceanic and Atmospheric Administration (NOAA).
Although the CME may not hit Earth directly, it may still liven up the Earth's auroras—the dancing, multicolored sky phenomena known as the northern and southern lights.
CMEs are studied by space weather experts since they can have consequences for modern society. Aside from causing more energetic auroras, CMEs can disturb the Earth's magnetic field and cause issues for electrical systems including power grids and navigation tools. These magnetic disturbances are called geomagnetic storms.
The NOAA's Space Weather Prediction Center (SWPC) issued a warning on Tuesday morning that a geomagnetic K-index of 4 was expected up to 3:00 p.m. UTC (11:00 a.m. ET). The K-index is used to characterize the magnitude of geomagnetic storms.
The agency added there could be weak power grid fluctuations and that aurora may be visible at high latitudes in places such as Canada and Alaska.
It comes after the SWPC issued an alert of a Type II radio emission from the sun on Monday morning. These emissions usually occur in association with CME eruptions.
Type II emissions were also reported on Sunday, along with another warning of a potential geomagnetic K-index of 4, and again on March 14th, possibly corroborating the reports by SpaceWeather. Newsweek has contacted NOAA for comment.
CMEs are large eruptions of plasma from the sun's atmosphere which travel through space at hundreds of miles per second.
How common CMEs are depends on where the sun is in its 11-year solar activity cycle. At its most energetic stage, called the solar maximum, CMEs can erupt several times per day according to Martin Archer, a space weather researcher at Imperial College London's Department of Physics—though most of those won't be directed at Earth.
"So-called Halo CMEs, those that look like an angel's halo in a coronagraph image because the eruption is directed approximately towards the camera and thus Earth, are much less common—between about 5-10 per month at solar maximum, whereas at solar minimum it wouldn't be unusual for no halo CMEs to be observed in a single month," Archer told Newsweek.
"This means that 3 near-miss CMEs in the span of a week isn't necessarily unusual at the height of solar maximum, but to happen now may be something of a statistical fluke.
"As the sun's activity ramps up over the next few years, we can expect more CMEs to be erupted both in general and towards our planet."
