Astronauts onboard the International Space Station captured a rare airglow around Earth. Instead of the usual purple and green, the atmosphere cast an orange hue.

ISS Captures Rare Orange Airglow

The photo was captured last month while the orbital outpost was about 250 miles above the continent of Australia. The orange-hued glow enveloped the upper atmosphere at it reacts to the ultraviolet radiation that comes from the sun.

An airglow is produced by the same mechanisms behind auroras. It occurs when molecules in the upper atmosphere, mostly nitrogen and oxygen, become too energized by the ultraviolet radiation from the sun, causing them to release energy. The result is a stunning display of light in the sky.

However, while auroras happen around the magnetic poles in both northern and southern hemisphere, the airglow envelops the entire planet in a bubble of light. The airglow is also difficult to detect from the ground, but it is visible from space at night time.

The airglow around Earth is usually color green with hints of yellow and purple; the orange cast is a rare sight. In 2016, skywatchers were even able to capture a photo of a rainbow airglow from atop a mountain in the Azores group of islands near the coast of Portugal.

At the time, NASA explained that the multicolored hue of the airglow was caused by sodium and oxygen atoms in the upper atmosphere. An approaching storm allowed the skywatchers to see the rainbow airglow and take a photo from the surface of the Earth.


NASA will be sending a spacecraft that will make close-up observations of the airglow in the upper atmosphere. Called the Ionospheric Connection Explorer or ICON, the mission will help scientists understand the point in which the atmosphere interacts with space weather.

ICON was initially set to be launched from Cape Canaveral in Florida on Wednesday, Nov. 7, at 3 a.m. aboard the Northrop Grumman Pegasus XL rocket. However, engineers "encountered an anomaly" that delayed the launch. No new launch date has been set as of this writing.

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