red air glow atacama
© https://www.instagram.com/yuribeletsky/
When the sun goes down, Chile's Atacama desert can be one of the darkest places on Earth. Last night, it was not. "I couldn't believe what I saw on the screen of my camera when I took the first image," reports photographer Yuri Beletsky, who recorded luminous bands of red rippling across the sky:

"The airglow was absolutely insane!" he says. "Parts of the Milky Way were barely visible because of the intense red glow."

Airglow is caused by a complex assortment of chemical reactions in the upper atmosphere. These reactions get started during daylight hours when the atmosphere is bathed in strong ultraviolet radiation from the sun. After sunset, the afterglow appears--usually green, but sometimes red. Beletsky is a veteran photographer of airglow, having captured it dozens of times from sites in Chile and the South Pacific. "The intensity of airglow varies, and sometimes it can be more prominent," he notes.

Last night, it was very prominent indeed. The red light came from OH radicals (chemical by-products of the daytime reactions) floating in a narrow layer 86 to 87 km above Earth's surface. Gravity waves propagating upward from the lower atmosphere impressed the thin red glow with a dramatic rippling structure.

"It seems the atmosphere is pretty active now," says Beletsky. "This is a good time to be alert for airglow."
"Absolutely insane airglow from the last night Yes, what you see on this image are not clouds ! That yellow/orangish light comes from the upper atmosphere. I couldnt believe what I saw on the screen of my camera when I took the first image. It seems the atmosphere is pretty active now and it allows us to witness some incredible views. The Milky Way at parts was barely visible ! I hope youll enjoy the view :) #Nikon #D810a"

Comment: Also reported on SpaceWeather.com and possibly related:
MAGNETIC UNREST

Late on May 5th, Earth entered a stream of solar wind flowing from a wide hole in the sun's atmosphere. More than 5 days later, Earth's magnetic field is still reverberating. "My magnetometer refuses to settle down," reports Stuart Green who sends these data from Preston, Lancashire, UK:

The squiggles in Green's chart represent changes in his local magnetic field caused by the buffeting of solar wind high overhead. "The sensor is buried in my garden about 0.5 meters below the surface in an East/West orientation," he explains. "This allows very sensitive measurements of magnetic declination during solar wind storms."

Sustained periods of unrest on May 5th and 6th coincided with G1- and G2-class geomagnetic storm. On those dates, the strange aurora named STEVE was sighted in multiple US states. Periods of quiet returned on May 7th through 10th, but even on those days Green's instrument picked up brief but intense magnetic disturbances. Activity should subside as Earth exits the solar wind stream on May 11th and 12th.

His chart recorder will probably do this again in early June. The solar-wind-spewing coronal hole is now rotating around the sun, lighthouse style, and it will be back in full force a little less than a month from now. Stay tuned.
magentic unrest may 5th 2018
Strange auroral arc 'STEVE' observed in US, farther south than usual