New Time-Lapse Video Showcases 'Airglow' Among Auroras Over Earth in Space

The Blaze often posts NASA's latest time-lapsed videos from space, but do they ever leave you asking more questions about certain elements you see in the universe than before you watched them? Photographer Alex Rivest recognized this and created a new time-lapse "dedicated to explorers who take pictures that make us ask questions."

Rivest starts off with two questions: "That thin-yellow atmospheric line separating earth from space, for example, that we see in all of the night shots provokes two questions: (1) how thick is this line? and (2) why is this line colored the way it is?" Here's how he answers it:

The visible yellow and green/blue capped line represents atmosphere reaching ~100km above the surface of the earth. The colors are not reflected light, and not pollution, but rather are light generated from the components in the atmosphere itself. Yes, the atmosphere gives off its own light, in a chemiluminescent process called "airglow" or "night glow."

Watch Rivest's video to see what he's talking about:

In the video, Rivest writes he first wanted to "bring the viewer's attention to the atmospheric line [...] and the 'Airglow.'" He also wanted to alter the orientation of the video compared to what we're used to seeing, because he explains "most of the images we see of earth show the planet at the bottom of the frame and space at the top of the frame," but how we view the planets is really "up to the viewer."

"I took artistic license with these images to present different ways to view our planet's movement in space," he wrote.

In a blog post, Rivest develes even more into specifics on the airglow, providing comparisons to help earthlings put into perspective some of these measurements. The ionosphere, the uppermost part of the atmosphere, is about 60 miles above the surface of earth, which he equates to about the distance you can drive on most highways for an hour -- or the distance between Boston and Cape Cod. It is this layer that helps Earth maintain a comfortable average temperature.

Rivest also explains the different colors you see in many of the famed time-lapsed videos. Yellow, he writes, is part of the "sodium layer," which is present due to breaking meteors and sodium atoms that remain in an excited state with a wavelength around 598 nanometers. The red in the "atomic oxygen" layer are caused by -OH radicals. This layer is often not uniform due to gravity. Oxygen and nitrogen combine to produce green light.

[H/T Wired]