Earth’s unique ‘Airglow’ visible from space, scientists explain the phenomenon
New Delhi (The Uttam Hindu): When imagining Earth from space, people often think of it as the “blue planet.” However, from the International Space Station in low Earth orbit, a remarkable sight becomes visible. At about 300 miles above the planet, bright layers of red, green, purple and yellow light can be seen in the upper atmosphere. Scientists call this natural glow “airglow,” which prevents the night sky from becoming completely dark and reflects complex atmospheric processes.
According to NASA, airglow occurs when atoms and molecules in the upper atmosphere become energized by sunlight. They release excess energy in the form of light called photons. While this process is similar to auroras, auroras are formed by high-energy solar wind particles, whereas airglow is powered by normal sunlight. Sometimes, collisions between ionized atoms and free electrons also produce light.
Even in the absence of light pollution, moonlight and stars, the night sky is never completely black due to this faint glow. Airglow accounts for nearly one-tenth of the total brightness of all stars combined. From space, it appears like a glowing bubble surrounding Earth and exists between 50 to 400 miles in altitude, where the ionosphere is located.
The colors of airglow come from different gases. Green light is the brightest and is produced by oxygen atoms. Red and other shades result from reactions involving nitrogen and oxygen. Some emissions occur in ultraviolet and infrared wavelengths that are not visible to the human eye.
This glow constantly changes because it is influenced by both solar energy and Earth’s weather systems. Scientists use airglow as an indicator of changes in the ionosphere, helping them study temperature, density and atmospheric composition. It also improves understanding of the link between space weather and Earth’s climate.
Researchers continue to study this phenomenon using images captured from the International Space Station, as it provides valuable insights into upper atmospheric activity.