• An ISS astronaut snapped a photo of the aurora borealis 'meeting' the Earth's airglow
  • They may look similar but they are actually very different processes
  • Airglow is ever present but auroras only occur at certain places under specific circumstances

An astronaut aboard the International Space Station (ISS) captured an image of the aurora borealis meeting the airglow in the atmosphere. Even if they tend to look alike, auroras and the Earth's airglow are not as similar as they seem.

It was only recently when an aurora was spotted with comet NEOWISE, with the visitor comet appearing clearly over the greenish aurora light.

For its Aug. 16 image of the day, NASA Earth Observatory also shared a stunning shot of the aurora, with the phenomenon appearing to meet with the airglow in the atmosphere. The image was taken by an Expedition 62 crew member aboard the ISS on March 16, 2020, using a Nikon D5 digital camera.

In the image, one can see the iconic bright green ribbons of the aurora borealis appearing to meet the faint red-yellow light of the airglow. The deep blue glow of the Sunrise, as well as city lights from British Columbia and Alberta in Canada, also join the light show from below.

Aurora and Airglow
Image: Aurora meeting the airglow in the atmosphere. This image was captured by an astronaut aboard the International Space Station. ISS Astronaut Photography/NASA Earth Observatory

Although they look similar and appear at similar altitudes, the aurora borealis and the airglow are quite different. One striking difference is the fact that the airglow occurs all around the Earth all the time, while auroras only appear in certain areas and under certain circumstances.

This is because airglow is the natural glow of the atmosphere that is relatively uniform across the globe. It occurs all the time as a result of sunlight interacting with the molecules in the atmosphere but, forms differently depending on the time of day.

On the other hand, the aurora borealis is not an ever-present phenomenon. It occurs as a result of interactions between solar energy and the Earth's magnetic field and, unlike the airglow, auroras typically only occur around the North or South Pole. What's more, auroras are not uniform but are highly structured, which is why they are observed as bright ribbons of colors in the sky.

"The dynamic nature of Earth's magnetic field moves the solar energy in irregular ways, causing each aurora event to be visually unique," NASA Earth Observatory said, further explaining that the reason why they appear similar in color is because the processes that cause both phenomena interact with the same atoms in the upper atmosphere.

Such images taken from the ISS not only provide stunning views of the Earth but, they are also very important to scientists as they provide a unique view of its processes.