On Earth, night is never completely black. The upper layers of the atmosphere tinted by an ‘airglow’, is caused by many physical reactions taking place and recently, an astronaut on board the International Space Station (ISS) captured a photo of this surprising show.
Taken from more than 400 kilometres above Australia, the photograph shared by NASA shows the magnificent night sky as a faint light is emitted from the upper atmosphere due to the way Earth’s atmosphere interacts with ultraviolet radiation from the sun. The world looks to be surrounded by an intense hue of colour, shining its light off the metallic body of the space station.
Some people may believe that this light is the result of nothing more than street lights saturating our cities. However, an illuminated city is actually the last place you’d be able to see this airglow, because it’s actually made in our atmosphere. To be more precise, it takes place in the upper atmosphere and is caused by a scene of strange interactions between ionized atoms, molecules and solar rays.
A brilliant cosmic ballet
There are numerous reasons as to why this glow exists. For example, it is said to be caused by photoionized atoms, meaning atoms from the sun, that have had their electrons torn away during the day, and then re-joined again during the night, hence releasing energy as they do so. But cosmic rays or even reactions involving mainly oxygen and nitrogen in the atmosphere are also susceptible to causing these glows to appear.
The ‘airglow’ is constantly present above our heads and although we can’t see it during the day, that’s because the sunlight is a lot more powerful and outshines it. However, if you’re lucky enough to find yourself camping or in the heart of the desert in the middle of the night, just look up and you might see these charm colours in the nights sky. To be able to see these lights in the night sky, it turns out all we have to do is get rid of our own sometimes.