HERE COMES THE SOLAR WIND: A solar wind stream is approaching Earth with wind speeds as high as 700 km/s. First contact with the fast-moving gas on Dec. 7-8 could produce G1-class geomagnetic storms and auroras at high latitudes. Observers around the Arctic Circle could be in for a fine light show.
The source of this solar wind stream is a hole in the sun's atmosphere, shown here in a Dec. 5th image from NASA's Solar Dynamics Observatory:
This is a "coronal hole"--a region where the sun's magnetic field has opened up, allowing solar wind to escape. Because this hole is broad, the emerging stream of solar wind is broad as well. It should influence Earth for several days after it arrives. Free: Aurora Alerts.
RED AIRGLOW OVER EUROPE: After nightfall on Dec. 2nd, the sky above Hungary suddenly became impressed by luminous ripples. "It was a once in a lifetime display of airglow in the middle of the light-polluted Europe," reports eye-witness Monika Landy-Gyebnar. Andras Pinter photographed the red corrugations outside the city of Mihályi:
"It was a very-very strong airglow above Hungary," says Pinter, who put together this animation to show the dynamics of the display.
Airglow is aurora-like phenomenon caused by chemical reactions in the upper atmosphere. Human eyes seldom notice the faint glow, but "on Dec. 2nd it was easily visible to the naked eye," adds Landy-Gyebnar. "To the layman, the bands might have looked like a layer of pale thin clouds, but my camera revealed their telltale red color."
The red color of the display was remarkable. Airglow is usually green, the color of light from oxygen atoms some 90 km to 100 km above Earth's surface. Where does the red come from? Instead of oxygen, OH can produce the required color. These neutral molecules (not to be confused with the OH- ion found in aqueous solutions) exist in a thin layer 85 km high where gravity waves impress the red glow with a dramatic rippling structure.
Meanwhile in Slovakia, the usual green color was visible through gaps in clouds. Roman Vanur photographed it from the city of Počúvadlo. "A great display!" he says.
Airglow is more common than you think. Browse the airglow gallery for more apparitions.
Realtime Airglow Photo Gallery
FAR-OUT STOCKING STUFFER: In space, not everything that twinkles is a star. For example, we present the Silver Stars & Moon Space Pendant:
On Dec. 3rd, using a helium balloon the students of Earth to Sky Calculus launched a payload full of these pendants alongside an array of cosmic ray sensors. Together they ascended to an altitude of 117,000 ft. The purpose of the sensors was to measure increasing levels of radiation in the stratosphere. The purpose of the pendants: to pay for the sensors. Our radiation monitoring program is completely crowdfunded, and the pendants are for sale.
You can have one for $69.95. Each pendant comes with a Christmas card showing the pendant at the edge of space and telling the story of its flight. More far out Christmas gifts may be found in the Earth to Sky Store. All proceeds support space weather research.
Realtime Space Weather Photo Gallery