A massive explosion on the far side of the sun that collided with a spacecraft was so large that if it hit the Earth, it could have triggered powerful geomagnetic storms.
The coronal mass ejection, or CME, was detected after it burst out of the sun's surface on July 24 by Europe's Solar Orbiter (SolO) spacecraft, which was on the other side of the sun at the time it collided, 32 hours later.
Typically, CMEs would take two to three days to reach the SolO craft, meaning that this CME was a powerful and fast-moving one. Imagery from the Solar and Heliospheric Observatory (SOHO) satellite around Earth also spotted the halo of the CME as it spread out around the sun, measuring it as traveling at around 3.4 million mph.
CMEs are huge plumes of solar plasma and magnetic fields that are flung out from the sun's surface when the sun's magnetic fields are tightly twisted and suddenly realign. Some CMEs are faster-moving and more powerful than others.
If this CME had hit the Earth, it may have led to strong or even severe geomagnetic storms, according to spaceweather.com.
"This was definitely a big event," George Ho of the Johns Hopkins Applied Physics Lab, co-principal investigator for the Energetic Particle Detector suite onboard Solar Orbiter, told the website.
SolO data showed a 10,000-fold increase of 50 MeV ions once the CME reached the craft. "This indicates a strong incoming interplanetary shock," he said.
"The reason CMEs can cause very different impacts on Earth's near-space environment is simply because they can be very different," Brett Carter, an associate professor in space science at RMIT University in Australia, told Newsweek in March.
"Some are really fast (sometimes reaching Earth within 1 day); others are slow (taking up to 3 days or so); some have 'sharper' shocks preceding them in the solar wind; but most importantly, the magnetic field that they carry within them has a major influence on how 'geo-effective' they are," he said.
When CMEs hit the Earth's magnetic field and atmosphere, the charged particles and magnetic influence can react with the ionosphere, causing geomagnetic storms.
"A geomagnetic storm is the alteration of the Earth's magnetic environment, this means when the magnetic fields that usually surround our Earth start to be distorted," Daniel Brown, an associate professor in astronomy and science communication at Nottingham Trent University, previously told Newsweek.
Geomagnetic storms come in a range of strengths, varying between G1 (minor) and G5 (extreme), according to the National Oceanic and Atmospheric Administration's space weather scales. G3 storms are considered "strong" and G4 are "severe"—categories that may have been achieved had this powerful CME hit the Earth.
"The amount of matter ejected, its speed, the associated magnetic fields, as well as how they interact with other already emitted particles from the sun, all add up to a bumpy environment moving outwards from the sun for our Earth's magnetic field to travel through," Brown said.
"The more prolonged, the stronger the interaction will be and the higher the likelihood of a strong geomagnetic storm."
The more powerful the storm, the greater the impact it could have on electrical equipment and the power grid, and the further south it may cause the Northern Lights to be visible.
G3 storms, which occur approximately 200 times per 11-year solar cycle, may cause auroras to be visible from Illinois and Oregon, while G4 storms, occurring around 100 times per cycle, may result in auroras being seen from as far south as Alabama and Northern California.
G5 storms, the most powerful, can result in aurora being spotted in Florida and southern Texas, as well as widespread voltage control problems and power blackouts.
Thankfully, this CME passed harmlessly out into space. The sun is approaching its solar maximum, however, meaning that increased numbers of more powerful CMEs and solar flares are to be expected in the lead-up to the maximum forecasted in 2025.
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Jess Thomson is a Newsweek Science Reporter based in London UK. Her focus is reporting on science, technology and healthcare. ... Read more
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