The powerful solar storm that struck Earth earlier this week treated an American astrophotographer to unexpected aurora displays during a shooting trip to California's Death Valley.
The sighting, documented in this beautiful image that shows the Milky Way arching above a purple glowing horizon, may be the southernmost of the recent aurora spree delivered by the sun storm of Feb. 27 and Feb. 28.
"I was indeed shocked to see this," Shari Hunt, a medical researcher and part-time astrophotography tutor who took the image, told Space.com in an email. "I was there in Death Valley for night photography and with the storm in California, we had clouds almost every morning blocking the galactic core. This was our last morning to shoot."
Hunt first noticed the strange glow when she directed her camera to the north, after setting up her gear at the popular Mesquite Flat Sand Dunes. In fact, the glow was so unexpected that she first thought she must have made a mistake.
"I thought I left my camera on auto white balance or something went wrong," Hunt recalled. "I had never seen an airglow like that! So, I took another shot and told my friend who was also there to check with her camera."
The two took repeated shots, all of which revealed the eerie glow that on the right-hand side of the image gradually gave way to light pollution above Las Vegas. The single sharp spot of light on the right is a car that appeared on a local road, Hunt said.
"After looking in post and seeing the changing or dancing, I knew we had captured the aurora," said Hunt. "We checked the aurora forecast as well, which also helped confirm it!"
Auroras occur when charged particles of solar wind arrive at Earth in high quantities and interact with Earth's atmosphere. Solar wind consists mostly of electrons and protons released from the sun's upper atmosphere, the corona. When these particles carry a magnetic field that has the opposite direction than Earth's magnetic field, the two fields connect and channel the solar wind particles deep into the atmosphere.
Due to the nature of Earth's magnetic field lines, the particles tend to penetrate the deepest above the polar regions, which is why most auroras remain restricted within the polar circles.
The solar storm that hit Earth on Tuesday (Feb. 28) generated a G3 geomagnetic storm on the five-degree scale of the U.S. National Oceanic and Atmospheric Administration (NOAA), the U.S. leading space weather authority. A G3 storm, according to NOAA, would usually only produce auroras in the northernmost U.S. states. The most severe G5 category, which usually occurs only a couple of times during each 11-year solar cycle, may light up the sky as far south as Florida.
At 36 degrees northern latitude, Death Valley is too far south for aurora displays during G3 storms, as traditionally understood. However, it appears that sensitive photographic equipment is now allowing astrophotographers to detect polar lights from much farther afield, even during milder events.
The same solar storm also boosted the southern polar lights, known as aurora australis, which thrilled skywatchers as far away from the South Pole as Perth in Western Australia. Perth is even farther away from the South Pole than Death Valley is from the North Pole. Still, an astrophotographer who identifies as Shelley on Twitter said the lights in Perth were visible even to the naked eye.
Aside from the beautiful aurora displays that stunned skywatchers all over northern and central Europe and North America, the storm also provided a taste of the darker side of space weather. SpaceX had to postpone the launch of a batch of Starlink satellites due to concerns that turbulent conditions in Earth's upper atmosphere may interfere with their ability to stay in orbit. Workers deployed on oil rigs in Canada reported that operations had to be temporarily suspended due to the storm's interference with GPS signals, which are used for precision navigation.
The current solar cycle, the periodic ebb and flow in the generation of sunspots and solar flares, is picking up momentum. The next solar maximum, the period of highest sun activity, is expected to come in 2025, so we are likely to witness more fabulous aurora displays as well as more space weather trouble in our technology-dependent world.