The Sun has been getting a bit more active lately, blowing out the odd solar storm or two. These waves of subatomic particles march across interplanetary space, and when they hit the Earth, they spark geomagnetic storms. Those in turn can result in displays of the northern and southern lights, or the aurora (borealis for the north, and australis for the south).
I love how it starts, with the Sun making its long, slow, shallow dive to the horizon. That’s a clear indication she was at a high latitude; at mid-latitudes like the United States and most of Europe, the angle the Sun makes toward the horizon is much steeper.
The odd motion of the water in the first few seconds of the video caught my attention as well. It wasn’t as jerky as I was expecting. Then I noticed some of the auroral streamers looked odd as well, and realized what was going on: Possberg was morphing from frame to frame, interpolating the motion between the shots. I described this in a post about a video from the Mars Curiosity rover; basically it’s just using a bit of math to smooth out the motion a bit. If an object appears in one part of a frame then is in a different place in the next frame, you can determine where it was at the moment halfway (or any fraction) between the two frames. It’s a perfectly fine thing to do, and it adds yet another unearthly level to the already surreal video.
As you watch, you’ll see most of the aurorae are green, which is normal. But there are also other colors that appear: purple, pink, even blue. All of these come from molecules and atoms of nitrogen and oxygen in the upper atmosphere, emitting light as they heal from their wounds after being slammed by subatomic particles from the Sun.
National Geographic has a story on how Possberg made this video, too, and it’s pretty interesting. She had the flu when she shot some of the video! That takes real dedication; it’s not like she was shooting these pictures in her back yard.
Right now I’m in Oregon for our Science Getaways trip. I’m really hoping the Sun gets some cosmic indigestion while we’re up there; those latitudes would be favored during a good aurora. I’ve never seen one myself, and given all these photos and videos I post, I think it’s about time I got my due.