The northern lights are undoubtedly one of Earth's most stunning sights, but if you really want to indulge in their ethereal beauty, then there are few better vantage points than the International Space Station (ISS).
NASA recently shared the time-lapse video below as part of its Image of the Day feature, and watching auroras never gets old. The stunning footage was shot on September 28, 2017, as the International Space Station made a pass from the northern Pacific Ocean, just south of Alaska, to the Gulf of Mexico, south of Florida. The skies over Canada are lit up with greenish lilac-tinged ribbons of light, flickering with an other-worldly glow. As the ISS descends down North America, the northern lights fade, but you might be able to spot a few cities in the US, including Chicago, Nashville, and Atlanta, before reaching the pitch-black Atlantic.
“The time-lapse imagery that we’ve been able to get of auroras is just fascinating to watch,” Will Stefanov, ISS program scientist for Earth observations at Johnson Space Center, told NASA Earth Observatory. “And just strikingly beautiful to be able to see that process, how the aurora shifts and moves like a live thing. And knowing that for that particular stretch of time, you are pretty much seeing what the crew saw in orbit.”
In the Northern Hemisphere, the aurora borealis, or "northern lights" are the product of cosmic forces journeying across the Solar System and clashing with Earth. Electrically charged particles are spat out of the Sun’s corona, its upper atmosphere, and drift through the Solar System in the form of solar winds. Once the charged particles from the Sun hit Earth’s magnetosphere, they release energy and excite gases in our upper atmosphere. The excitement causes ionization of the atmospheric molecules and the release of light photons. Oxygen produces green and yellow light, while nitrogen creates red and blue light.
They are most clearly seen near Earth’s poles, most notably in the Northern Hemisphere, but the aurora australis is also seen in the depths of the Southern Hemisphere too, due to the geomagnetic field around the planet. The magnetic field will initially deflect the charged particles, causing them to flow around the planet and hit near the polar regions where the magnetic field is weakest.
There's still much to learn about this incredible phenomenon. Just last year, a team of citizen scientists, aurora-hunting photographers, and space physicists described a previously undocumented form of northern lights in southwest Finland.