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A ‘cannibal’ coronal mass ejection (CME) that’s heading towards Earth means an aurora could be visible this week in certain US states.
It was announced earlier this week that geomagnetic storm watches are in effect for 17-18 August, and CMEs are expected to overtake each other and gobble one another up, hence the ‘cannibal’ bit.
Excitingly, a blue-green aurora may also be visible in certain states, and stargazers looking to the sky between 11:00pm and midnight are likely to see the aurora at its brightest.
CMEs - which are large expulsions of the Sun’s plasma - were launched from the star’s surface this week and are expected to hit Earth’s atmosphere any day now.
These clouds of hot plasma are extremely high energy and when they do occasionally hit earth, electrons in the plasma speed up along the magnetic fields leading to Earth's poles.
Here, the electrons crash into oxygen and nitrogen atoms alongside other molecules in our planet’s upper atmosphere.
This stirs the atoms to a higher energy state, prompting them to release excess energy, which looks like the blue-green glow of the Southern and Northern Lights.
On Tuesday (16 August), the U.S. National Oceanic and Atmospheric Administration's (NOAA) Space Weather Prediction Centre (SWPC) said in a statement: “Geomagnetic responses are likely to escalate to G3 (Strong) conditions on 18 Aug due to the arrival at or near Earth of multiple coronal mass ejections (CMEs) that have departed the Sun since 14 Aug.”
The NOAA continued: “Impacts to our technology from a G3 storm are usually minimal. However, a G3 storm has the potential to drive the aurora further away from its normal polar residence, and if other factors come together, the aurora might be seen over portions of Pennsylvania, Iowa, to northern Oregon.”
The 14 states where the aurora may be visible are Washington, Montana, North Dakota, South Dakota, Minnesota, Wisconsin, Michigan, New York, Vermont, New Hampshire, Rhode Island, Massachusetts, Connecticut and Maine.
On Tuesday, former NASA astronomer Dr. Tony Phillips explained: "This could be a 'Cannibal CME' event.
"In other words, the second CME might overtake and gobble up the first, creating a mish-mash of the two.
"Cannibal CMEs contain tangled magnetic fields and compressed plasmas that sometimes spark strong geomagnetic storms."
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