Yesterday’s M7.79 major solar flare produced the third large Earth-directed coronal mass ejection (CME) of the week. As a result, SWPC has posted yet another geomagnetic storm watch for Saturday and Sunday.
The flare emerged from the same active region as the previous CME producing flares this week. The sunspot region is designated beta-gamma-delta based on it’s magnetic structure. BGD is the most complex structural designation for sunspot regions and is the most likely to produce large flares and CMEs. The first CME produced an amazing show on northern lights show of Monday night with G4 (KP=8) storming when the plasma cloud arrived at Earth. The second CME was not oriented the right way to produce widespread aurora, but it did push the KP to 5 – Ian Griffin was able to capture a nice glow in New Zealand and Snoozy (@SussanSays) captured these in Tasmania:
— Snoozy (@SussanSays) June 26, 2015
This flare was particularly long duration. The flare just lasted just over an hour, but x-ray flux was continuing to decrease almost 3 hours later. Generally the longer duration the flare the more likely it is to produce a CME, and it produced a big one. Even though the flare happened a little west of the Earth-Sun line, there was still a halo signature and a large portion of the CME is Earth directed. The CME is traveling at around 1500 km/s, and is expected to arrive at Earth on Saturday. As a result SWPC has posted a G2 storm watch Saturday and Sunday:
We’ll be updating the exact timing of the storm’s arrival as we know more, so be sure to follow @northlightalert on Twitter for updates. It’s important to keep an eye on the data because we won’t know until the storm arrives if it is oriented correctly to disrupt the Earth’s magnetosphere and light up the sky. Space weather is an emerging field, so the prediction are still difficult to nail precisely. Aurora hunting takes a lot of patience, but when all the factors come together just right seeing aurora is an experience you will never forget.
Between now and when the storm arrives, read up on our guide with last minute tips on how to see aurora.