The Aurora Seen Around The World

Think back to St. Patrick’s Day. Do you remember what you were doing? Hopefully you were wearing something green. And, hopefully, you didn’t leave anything green in the gutter behind the bar (e.g. undigested lunch or beverages or a mixture of the two). If you did, we don’t want to hear about it. It’s unpleasant enough that you had to read that and have that image in your mind. Apologies if you are eating.

If your mind was lucid enough that night, or the following night, did you remember to look up to the northern sky? Or, right above you, if you live far enough north? (Swap “north” for “south” if you live in the Southern Hemisphere. Everything is backwards there.) Was it a clear night?

If you answered “no” to the first two questions and “yes” to the third question, you missed out on an opportunity to see something green in the sky – one of the great atmospheric wonders of the world: the aurora. If you answered “yes” then “no”, tough luck. The lower atmosphere does not always cooperate with the upper atmosphere. If you answered “yes” on everything and still didn’t see the aurora, then you need to move closer to your nearest magnetic pole. Or, away from light pollution. (Although, truth be told, it is possible to live too far north or south to see the aurora. But, not many people live there. Those who do rarely have to worry about light pollution.)

If you forgot to look up at the night sky on 17-18 March 2015, you have no excuse. The media was hyping the heck out of it. That link is just one example of media predictions of the aurora being visible as far south as Dallas and Atlanta. While I couldn’t find any photographic evidence that that actually happened, there were people as far south as Ohio, Pennsylvania and New Jersey that saw the aurora. In the other hemisphere – the backwards, upside-down one – the aurora was seen as far north as Australia and New Zealand, which is a relatively rare occurrence for them. And there are no shortage of pictures and videos if you want proof: pictures, more pictures, even more pictures, video and pictures, video, and a couple more short videos here, here and here.

Now, we already know that VIIRS can see the aurora. We’ve covered both the aurora borealis and aurora australis before. This time, we’ll take a look at both at the same time – not literally, of course! – since the Day/Night Band viewed the aurora (borealis and australis) on every orbit for an entire 24 hour period, during which time it covered every part of the Earth. So, follow along as VIIRS circled the globe in every sense of the word during this event.

First, we start with the aurora australis over the South Pacific, south of Pitcairn Island, at 10:15 UTC on 17 March 2015. We then proceed westward, ending over the South Pacific, south of Easter Island at 08:16 UTC on 18 March 2015. Click on each image in the gallery to see the medium resolution version. Above each of those images is a link containing the dimensions of the high resolution version. Click on that to see the full resolution.

Notice how much variability there is in the spatial extent and shape of the aurora from one orbit to the next. Everything is represented, from diffuse splotches to well-defined ribbons (which are technical terms, of course, wink, wink). You can see just how close the aurora was to being directly over Australia and New Zealand. And, if you looked at the high resolution versions of all the images (which are very large), you might have seen this:

VIIRS DNB image of the aurora australis, 18:39 UTC 17 March 2015

VIIRS DNB image of the aurora australis, 18:39 UTC 17 March 2015.

Just below center, the aurora is illuminating gravity waves forced by Heard Island. The aurora is also directly overhead of it’s “twin”, “Desolation Island” (aka Îles Kerguelen, upper-right corner right at the edge of the swath), although it looks too cloudy for the scientists and penguins living there to see it. (How many more Remote Islands can I mention that I’ve featured before?)

Now, I’m a sucker for animations, so I thought I’d combine all of these images into one and here it is (you can click on it to see the full-resolution version):

Animation of VIIRS DNB images of the aurora australis, 17-18 March 2015

Animation of VIIRS DNB images of the aurora australis, 17-18 March 2015.

Here, it is easier to notice that the aurora is much further north (away from the South Pole) near Australia and New Zealand and further south (closer to the pole) near South America. This is proof that the geomagnetic pole does not coincide with the geographic pole. This also puts the southern tips of Chile and Argentina at a disadvantage when it comes to seeing the aurora, compared to Australia and New Zealand.

Now, repeat everything for the aurora borealis – beginning over central Canada (07:57 UTC 17 March 2015) and ending there ~24 hours later (07:40 UTC 18 March 2015):

Basically, if you were anywhere in Siberia where there were no clouds, you could have seen the aurora. (For those who are not impressed, Siberia is a big area.) Did you see the aurora directly over North Dakota? (I showed a video of that above.) Did you notice it was mostly south of Anchorage, Alaska? (Typically, it’s over Fairbanks.) It was pretty close to Moscow and Scotland, also. But, what about the sightings in Ohio, New Jersey, and Germany? It doesn’t look like the aurora was close to those places…

For one, the aurora doesn’t have to be overhead to see it. Depending on the circumstances (e.g. auroral activity, atmospheric visibility, light pollution, etc.), you can be 5 degrees or more of latitude away and it will be visible. Second, these are single snapshots of an aurora that is constantly moving. (We already know the aurora can move pretty fast.) It may have been closer to these places when VIIRS wasn’t there to see it.

Lastly, here’s an animation of the above images, moving in the proper clockwise direction, unlike in that backwards, upside-down hemisphere:

Animation of VIIRS DNB images of the aurora borealis, 17-18 March 2015

Animation of VIIRS DNB images of the aurora borealis, 17-18 March 2015.

If you want to know more about what causes the aurora, watch this video. If you want to know why auroras appear in different colors, read this. If you want to know why aboriginal Australians viewed the aurora as an omen of fire, blood, death and punishment, and why various Native American tribes viewed the aurora as dancing spirits that were happy, well, you have a lot more reading to do: link, link and link.

4 thoughts on “The Aurora Seen Around The World

  1. Curtis,

    I was really impressed with your aurora images from VIIRS for the St Patricks day space weather storm. I would love to explore the idea of a realtime aurora page. We have a model that we use to forecast the aurora at

    http://www.swpc.noaa.gov/products/30-minute-aurora-forecast

    Your data would be a fantastic addition to this site and could make an entire product by itself.

    How much processing did you have to do to the VIIRS images. I know there are issues with scattered light.

    Cheers
    Rodney

  2. Hi Curtis – really fascinating work. I’ve come across your work because I was searching for any data sources using equirectangular global projections of auroral data (preferably with alpha channels and no underlying vector map artwork) for some data visualisation software I’ve been working on – perhaps the underlying data you’ve used for these animations could be used (rather than a polar stereographic projection)? I understand these images are derived from different satellite passes, so are not temporally adjacent – is there anything around that images the South or North Pole’s auroral data in a single image that might be animated? Thanks! Peter

    • Hi Peter – The VIIRS instrument shown here provides static images of the aurora. The animations are comprised of individual satellite overpasses separated in time by ~100 minutes. It is possible (although likely difficult) to extract the aurora signal from the data and plot that to any map projection you wish. And it is certainly possible to use alpha layers to provide transparency to combine this data with any underlying background you want. But, you will be limited by the fact that this satellite instrument does not provide animated images like a high-powered video camera would of an aurora.

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