Two CME hit Earth Today, producing Aurora in Washington
The Earth experienced a double impactor event overnight and into this early morning (as far as all of us in North America are concerned).
This was the result of two coronal mass ejections reaching us in sequence. Coronal Mass Ejections, or CME's are large expulsions of plasma from the Sun’s corona. They can eject billions of tons of material. CME's travel from the Sun at speeds that can exceed 3000 kilometers per seconds.
The two impacts can be seen in this capture from Nasa's ENLIL Spiral.
The yellow dot to the right of center is Earth. You can see two red and white bands extending past the yellow dot; a glancing blow. But those two events combined to create a substantial aurora after interacting with our magnetic field. An aurora that was seen as far south as Seattle, Washington (by the naked eye) and as far south as Ladd Marsh, Oregon (with long exposure photography).
Today's solar storm raised the Kp-index to just below level 7.
The Kp-index is a geomagnetic activity index that is based on 3-hour measurements from ground-based magnetometers around the world. A Kp-index of this level is considered to be just below "severe" levels, allowing the aurora to reach as far south as it did today.
The two solar flares, shown in the graph below, were released over a day apart, but because of the impulsive nature of the first (far right, shorter spike in the graph) and the "long-duration" of the second (seen with the long, sloping return to normal) allowed the second to almost catch up to the first, doubling the impact.
For a visualization of how this event unfolded, look to the two images below. The first shows normal conditions before the impact. The second shows how hard our magnetic field was hit today.
Even to the untrained eye, this impact was substantial.
For another visualization, the chart below is an amalgamation of numerous data points. The red indicates geomagnetic effect, the blue is the Polar Angle (Phi) of the Magnetic Field, orange represents the density of space as we travel though it, purple shows the speed of the CME impact and green shows temperature. All of these data points show a hefty disruption as impact occurred.
The Sun experiences sunspot minimum and maximums, as well as other cyclical variations throughout. For more information on this subject, I recommend Suspicious Observers on YouTube as well as their companion website, spaceweathernews.com. The operator of that YouTube page and the website, Ben Davidson, is a true authority on the subject and has dozens of video's that explain this phenomenon is a clear and concise fashion. It is a channel I highly recommend. Here's a link to today's video.