Dark river of Milky Way, with airglow
Daniel McVey posted this photo on EarthSky’s Facebook page earlier this week. It’s a gorgeous shot of the Milky Way and airglow, but Daniel didn’t post it for its beauty alone. He also wanted an opportunity to talk about dark skies. You need a dark sky to see the Milky Way, and airglow, and to acquire a photo like this one. Daniel wanted to remind everyone of an upcoming event – International Dark Sky Week, which starts one week from today, April 5 – 12, 2013. It’s designed to raise awareness about the effects of light pollution and offer some simple ways to use light responsibly.
And airglow? Here’s Daniel’s explanation from his blog:
What is airglow? When oxygen particles high in our atmosphere interact with sunlight, they become excited or ionized during the day. At night, as the particles return to their normal state, they release visible light and microwaves. The green glow is produced by oxygen atoms about 60 miles (100 km) high in the atmosphere. The red glow is from oxygen atoms higher than 60 miles in the atmosphere. The effect is likened to placing a glow-in-the-dark sticker under a lamp for several minutes then turning the lamp off to witness the glow from the sticker.
Airglow is a signature of a dark sky.
Thank you, Daniel!
Bottom line: Milky Way, airglow, and a reminder of International Dark Sky Week, April 5-12, 2013, from photographer Daniel McVey.