The International Space Station (ISS) recently shared a striking image showcasing the vibrant hues of Earth’s atmosphere from space, with the planet enveloped in a golden-yellow glow. Captured by NASA astronaut Don Pettit, the photo also features twinkling stars in the background. The Instagram caption highlighted the colorful layers: green from atomic oxygen, orange from hydroxyl radicals, and red from airglow excited by solar activity.
These colors result from a phenomenon called airglow, where atoms and molecules in the upper atmosphere emit light after being excited by sunlight. This can occur either when sunlight energizes atoms or when ionized particles capture free electrons, releasing photons in the process. Unlike auroras, which are triggered by high-energy solar wind particles and are temporary, airglow is continuous, forming a faint, glowing envelope around Earth. It is much dimmer than auroras and barely visible from the ground, but it marks the boundary where Earth meets space.
The ISS, a collaborative project among NASA, Roscosmos, ESA, JAXA, and CSA, serves as a laboratory, observatory, and platform for climate monitoring and health research, offering breathtaking views and scientific insights from orbit.
