Earth’s Skies May Dance In Auroral Green St. Patrick’s Day

A solar flare in the early morning hours of March 15 CDT sent a cloud of high-speed subatomic particles called a coronal mass ejection toward the Earth. It’s expected to arrive overnight tonight through Sunday. A disk blocks the sun in this photo taken with the Solar and Heliospheric Observatory (SOHO), allowing a better view of the cloud. Credit: NASA / ESA

I’ve got green on my mind and it’s not because I’m Irish. On March 15 a magnetic filament – a strand of solar flame silhouetted against the sun’s brilliant disk – erupted in a long-duration flare that sent a blast of solar plasma directly toward the Earth. Traveling at 2 million miles per hour, the cloud of high-speed electrons and protons will slam up against our planet’s magnetic bubble and possibly touch off an auroral storm.

Auroral display over Duluth Oct. 8, 2012. The green color, the most common seen in northern lights, is caused by oxygen atoms in our atmosphere energized by high-speed electrons from the sun. When the atoms return to the “unexcited” state, each releases a bit of green light. Photo: Bob King

Minor auroras are forecast for mid-northern latitudes tonight March 16 with a chance for a major storm on Sunday. If you live in the Arctic, get ready for a good show – chances for a major to severe storm stand at 70% Sunday (20% for mid-latitudes).

Wide-field view of the same coronal mass ejection taken by SOHO around 3 a.m. CDT March 15. Venus is to the lower right of the sun. Credit: NASA / ESA

These are the best numbers I’ve seen in some time, so be on the lookout this weekend for green rays step-dancing across the northern sky.

As always, keep an eye on the Kp index and the extent of the auroral oval, both of which are useful indicators of auroral activity. If the Kp index bar is colored red (equal to 5 or more), there’s a good chance auroras are out at least for the northern U.S. and southern Canada.

As I write this in the wee hours of Saturday morning, the index is already rising and auroras appear to be pushing into the far northern U.S. If it wasn’t for a heavy snow falling, I’d go out for a look-see right now. More updates later today.

5 Responses

  1. Wayne Hawk

    Aloha Astro Bob!

    I know there are more than a few folks out there who are worried about this M1-Class solar flare that is sending lots of “charged particles” directly towards our humble planet and (no fault of yours, Astro Bob) having headlines that read, “Sky’s to turn green on St. Patrick’s Day” don’t help any.

    NO. The sky will be cloudy, partly cloudy, partly sunny or clear and BLUE during the daylight on St. Patrick’s Day. Not until it is dark enough to see the auroras during the night will there be a chance that the sky will turn green, along with all the other beautiful colors the auroras have shown us in the past. But you have to live far enough north to see them. Those of us who live close to the equator, like me in Hawaii, probably have a better chance of seeing NO auroras at all.

    Hopefully, there will be no ill effects from this solar flare, however, no one knows for sure, now do they?

    Aloha For Now!

    1. astrobob

      Hi Wayne,
      Auroras are always rare for you, but then living in Hawaii has other benefits. The flare’s just an M1 class – moderate not big – so there won’t be any bad effects

  2. Judy

    Thanks for all the info. My husband and I took turns getting up several times during the night, but no Northern Lights. The skies here in Massachusetts were brilliantly clear and star-filled by 2:00 a.m. Maybe tonight????

    Your info is VERY helpful. God to find things in one place, and explained so clearly

    1. astrobob

      Thanks Judy! The aurora did come out – a spectacular show – but VERY late. More in today’s blog.

Comments are closed.