An atmospheric effect called airglow makes Earth look other-worldly

Earth isn’t always blue and green.
Earth isn’t always blue and green.
Image: NASA
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In October, an astronaut on the International Space Station snapped a photo of what looks like another world, glowing yellow and orange. But that photo, taken from 250 miles over Australia, is just Earth with a strange tint due to an atmospheric phenomenon called airglow.

You may recall from your high school science class that Earth’s atmosphere is a layer of gases surrounding the planet, protecting us from the sun’s damaging ultra violet rays. As UV rays hit the Earth’s lower atmosphere, they energize molecules in the air, and that energy is released as light.

Though there is usually some degree of airglow in our atmosphere, it’s not always visible, and the bands of colors we see vary based on the atoms in different layers of the atmosphere. In the ISS photo, the airglow appears yellow and orange, but airglow as seen from Earth usually appears red and green.

NASA is studying airglow to better understand how our atmosphere works. Because the atmosphere is the buffer between Earth and space, studying it can help scientists better understand the link between the weather on Earth and in space. To that end, NASA plans to launch a new satellite called the Ionspheric Connection Explorer (ICON); the launch was originally scheduled for today (Nov. 7), but was postponed due to a glitch in the rocket. Once launched, it will monitor the Earth’s atmosphere from its orbit at around 360 miles above earth.