NASA has shared a beautiful image taken from the International Space Station (ISS), which shows Earth wrapped in a soft orange haze along the horizon. In the caption of the photo posted on Instagram, the space agency wrote, "In this image of Earth from the @ISS, Earth appears to be bathed in orange light." The effect isn't a sunset or camera glitch; it is called airglow, a natural light show happening 80 to 100 kilometres above the surface.
Airglow happens when molecules and atoms in the upper atmosphere absorb energy from solar radiation during the day. At night, those excited particles release that energy as faint light. The process is similar to how neon signs work, just on a planetary scale.
Unlike auroras, airglow is present every night across the globe. It's just usually too faint to notice without the dark, unobstructed view from orbit. The ISS gives us a front-row seat to this subtle, constant chemistry experiment playing out in our sky.
"This glow can be a variety of colors, including red, green, purple, and yellow," NASA wrote. The colour depends on which gases are involved and at what altitude. Green often comes from oxygen around 100 km up; meanwhile, red colour happens when oxygen appears higher, near 200 km. Orange, yellow, or purple can show up when sodium, hydroxyl radicals, or other molecules join the mix.
Describing the image, NASA said that the image captured a bright "orange airglow outlining Earth's horizon beneath the starry expanse of space".
"A dark, shadowed portion of the space station is visible on the right side of the image," it added.
The image posted on Instagram gained significant traction. "The universe is beautiful!" one user wrote in the comment section, praising the image.
"Stars can be seen through the atmosphere and land??? Zoom in and... Wakey Wakey people!!" another wrote.
"It's mind-blowing how the ISS captures the fragility of our atmosphere. It looks like a scene from a sci-fi movie, but it's our beautiful reality. Perspectives like this remind us why we must keep exploring the deep void. Ad Astra!" a third user added.
