The aurora is very active tonight! Thankfully, high pressure has granted us mostly clear skies to watch them. Also on our side is the moon, which is just a crescent tonight. We need dim and clear conditions for good viewing so this is a good thing.
From what I can tell, on Friday the Sun launched a powerful coronal mass ejection, or CME, directly toward Earth. It arrived late Saturday so now the thermosphere is all colorful and the northern hemisphere is abuzz with northern lights that should last at least through Sunday night. We do have clouds moving in from the west, but the central and eastern UP should have a good view for most of the night. Saturday night it was seen as far south as Colorado .
I'm going to be a bit candid and say that I really don't know much about the aurora, but as a broadcast meteorologist, I am often asked about the aurora borealis, or northern lights, and when I was new at this job I had no clue what to say. In truth, I sometimes still don't because the aurora is not really a meteorological phenomenon. In four years at Valparaiso University it never even came up once in class that I remember. Most of Earth's weather happens in the troposphere, Earth's shallowest and lowest layer of its atmosphere. The aurora occurs way up in the thermosphere , the largest and highest layer, which has weather, but none that impacts us at the surface.
Since moving to Upper Michigan over a year ago, however, where I can see it much more often than in Chicago, I have learned a bit more about it from internet and Facebook sources. I thought I would share a few of them with you.
I often find simple and reliable info at spaceweather.com , where you can see many great user-submitted pictures, some of which feature local photographers here in the UP. The aurora's intensity is measured by the Planetary K index (aka the Kp index) which is a scale of 0 to 9. The higher that number is, the further south it can be seen. For the mid-latitudes where we are, the index needs to be about 4 or 5 to be really visible. This current geomagnetic storm is being reported to be a 6.
Other sources for info on the aurora can be found through Michigan Tech whose website offers even more links for information. There are also numerous sources through social media, like Aurora Borealis Notifications .
If you see the aurora, please visit our Facebook page and let us know where and when, and PLEASE send us pictures. We'll share them and use them as Pride of the UP photos.