Auroras in California are rare and remarkable. They are visible to the naked eye typically no more than a few times a decade.
The May 28th display was even more remarkable considering the phase of the sunspot cycle: The sun is rapidly plunging toward Solar Minimum.
Sunspots are scarce and solar flares are weak at best. Nevertheless, we just experienced a strong G3 geomagnetic storm on May 28, 2017.
The CME that sparked auroras over California this weekend was hurled toward Earth by a seemingly minor magnetic reorganization in the sun’s atmosphere.
Compared to many other photos of the May 28th geomagnetic storm, this one is noteworthy. as it was taken in California.
As Dan McBride explains: “I saw the magnetic storm alert at 11:00pm. When the K-index hit 7, I left my house and drove for 1 1/2 hours to the helipad at Big Hill Lookout, west of Lake Tahoe. I could barely see it, but after my first test shot I knew I had just caught purple pillars from California at latitude 38.8 degrees N.”
No sunspots are required for space weather phenomena.