Wait a minute... maybe we WILL see a little aurora tonight, March 13-14
A series of rays or pillars with pink tops and green bottoms dance along the northern horizon Friday night, March 12, 2021. Both colors are caused by the excitation of oxygen atoms as they're bombarded by solar electrons. It's a battle out there! Bob King The northern border states may been in for another, albeit small, aurora display tonight, March 13-14. The latest 3-day forecast from NOAA's space weather gurus fires my optimism. Over the years, I've used Kp 5 as the minimum indicator of magnetic hullabaloo that has to occur before the aurora shows up in the Duluth, Minn. region, but lately I've noticed that sometimes we'll get good activity — low bright arcs and faint rays — when Kp = 4. Just to refresh, Kp is a number from 0 to 9 that indicates how disturbed Earth's magnetic field becomes when it's affected by particle blasts from the sun. Those include material ejected during solar flare eruptions and from coronal holes. Kp is an index of activity...