Astrophoto: Airglow Shining Like an Aurora

By Nancy Atkinson - July 10, 2013 04:45 PM UTC | Planetary Science

Look closely at this beautiful serene view taken by

Miguel Claro

from Portugal. Not only is it a stunning view of the skies over Lake Alqueva in the Dark Sky Alqueva Reserve in Portugal, but there are also several scientifically interesting features here. Of course, visible is the arc of the Milky Way, filled with colors and light. Seen here is the most central region of the Milky Way, located near the constellations of Scorpio and Sagittarius, where you might recognize many deep sky objects like the Lagoon Nebula (M8) and the Trifid Nebula (M20).

The "glow" seen here is not the aurora borealis, but instead it is

airglow

(atmospheric chemiluminescence), which is a photochemical reaction that occurs high in the atmosphere when various atoms get excited from the ultraviolet radiation from the Sun. Miguel explained via email that the yellow light is from emissions from sodium atoms in a layer at 92 km, and above it, is green light from oxygen atoms in a layer 90-100 km high. This emission layer is clearly visible from earth orbit, which we've seen in many images and videos taken from the ISS.

[caption id="attachment_103411" align="aligncenter" width="580"]

An annotated version of the Milky Way and airglow seen in the Dark Sky Alqueva Reserve in Portugal. Credit and copyright: Miguel Claro.[/caption]

"Reflected in the peaceful lake and due to the polarization effect of water, we could clearly see the entire constellation of Scorpius with the real color of each star naturally saturated," Miguel said via email, "due to this polarization and blurred effect, caused by the slowly movement of water during the long exposure. The orange color of the Red Supergiant Antares could be easily distinguished from the blue color of the Subgiant star, Shaula, in the end of tail."

Miguel used a Canon 60Da - ISO 1600; 35mm lens at f/2; Exp. 15 secs. Mosaic of 23 images, taken on June 15, at 02:35 AM.

You can see

another image on Miguel's website

taken on the same night and place, where airglow is visible with the Andromeda Galaxy (M31) and

still another with the Big Dipper and gravity waves with the airglow.

Nancy Atkinson

Nancy Atkinson

Nancy Atkinson is a space journalist and author with a passion for telling the stories of people involved in space exploration and astronomy. She is currently retired from daily writing, but worked at Universe Today for 20 years as a writer and editor. She also contributed articles to The Planetary Society, Ad Astra (National Space Society), New Scientist and many other online outlets.

Her 2019 book, "Eight Years to the Moon: The History of the Apollo Missions,” shares the untold stories of engineers and scientists who worked behind the scenes to make the Apollo program so successful, despite the daunting odds against it. Her first book “Incredible Stories From Space: A Behind-the-Scenes Look at the Missions Changing Our View of the Cosmos” (2016) tells the stories of 37 scientists and engineers that work on several current NASA robotic missions to explore the solar system and beyond.

Nancy is also a NASA/JPL Solar System Ambassador, and through this program, she has the opportunity to share her passion of space and astronomy with children and adults through presentations and programs. Nancy's personal website is nancyatkinson.com