Nature has dealt humans a rough hand lately, with hurricanes, fires and a huge earthquake. But over the past week, it also produced an incredibly beautiful spectacle with astonishing frequency: an aurora painting a colorful path across the night sky, even in areas where the phenomenon isn't ususally seen.
The bountiful auroras are actually thanks to the closest solar equivalent of Earth's giant storms: a hurricane on the sun. While auroras are usually limited to a ring around the poles—about the latitude of Alaska and Scandinavia in the Northern Hemisphere—thanks to this week's solar activity, they have been spotted in places as far away as Michigan and Wisconsin.
Here's how the phenomenon works. From Earth, the sun seems comfortably predictable. It rises in the east, sets in the west, marching across the sky like a steady, superpowered light bulb. But that's an illusion brought on by our distance from the star: 92 million miles.
Point a special telescope at the sun and the perfect facade disappears, revealing the star's inner turmoil. The sun is a star like any other, which means it's basically a gigantic ball of hot, energetic matter, and with that much energy in play, it's bound to get messy.
That's because the sun is shaped by a giant magnetic field, which knots up the super-hot, charged particles called plasma that comprise the outer layer of the sun. Oh, and the magnetic field completely flips directions every 11 years. It last flipped four yeas ago, but our favorite star isn't going into the quiet period of its cycle without a fuss.
The magnetic field can tangle enough plasma to cause a cold, dark sunspot to form on the sun; such spots are the launch sites for a couple of types of solar outbursts. The past week has been marked by a series of strong solar flares, including one that was the largest seen in more than a decade. The latest came at around noon ET on Sunday.
Some flares are accompanied by large solar burps of plasma called coronal mass ejections, and sometimes Earth happens to be in their path. That's been the case with at least two coronal mass ejections over the past week—the result being auroras that were visible quite far from the poles.
Auroras are the result of charged particles inside the coronal mass ejection colliding with molecules of Earth's atmosphere. As they hit, they pass along some of their energy, but not very efficiently, so some are released as a little burst of typically greenish light. From Earth, a series of those collisions creates the dance of color we call an aurora, or the Northern Lights (although they can also be seen in the Southern Hemisphere).