If you’re looking for some free entertainment on Wednesday night, just tilt your head back. There’s a chance you could get treated to one of the most spectacular light shows that nature has to offer.
This past Sunday, July 21, a massive explosion on the surface of the Sun, called a coronal mass ejection (CME), occurred. This happens when powerful magnetic fields on the Sun’s surface get stretched to the point of breaking. Eventually they snap, sending enormous amounts of solar particles shooting off into space, some of which can head towards Earth.
On Wednesday, those particles are set to arrive. But fear not, they aren’t dangerous to humans. Instead, they will set off a chain reaction that may lead to vivid auroras over parts of the United States that don’t regularly get to see them. According to the National Oceanic and Atmospheric Administration, auroras could be visible over northern and upper midwest states from New York to Idaho on the evening of Wednesday July 24.
The bright, swirling lights of auroras like the Northern Lights are caused when solar particles collide with oxygen and nitrogen in the atmosphere. The molecules get excited by the collision, but as they lose the energy they picked up, they begin to glow. When there are particularly powerful explosions on the Sun’s surface, like Sunday’s CME, unusual amounts of particles are shot at the Earth, resulting in auroras in unusual places.
Although Sunday’s solar storm might seem ginormous compared to, say, the bomb in Oppenheimer, it was actually pretty small as solar storms go. NOAA rated it as a G2, the second weakest variety. While it’s not dangerous to humans, the effects of the storm do pose a slight threat to some technology, as it could interfere with HF radio signals in some parts of the world and may require spacecraft like satellites to take some corrective maneuvers to avoid damage.
The incoming storm pales in comparison to another solar storm back in May, which was rated a G4, the second most powerful variety. During that memorable episode, five separate CMEs occurred in short order, combining their energy and particles together thanks to a sunspot about 16 times the Earth’s width. The resulting auroras could be seen as far south as Alabama.
