'CANYON OF FIRE' OPENS, SPITS A CME TOWARD EARTH: Yesterday, Nov. 5th, a filament of magnetism in the sun's northern hemisphere became unstable and erupted. The blast split the sun's atmosphere, hurling a CME into space and creating a "canyon of fire," shown here in a movie recorded by the Solar Dynamics Observatory:
The glowing walls of the canyon trace the original channel where the filament was suspended by magnetic forces above the sun's surface. From end to end, the structure stretches more than 200,000 km--a real Grand Canyon.
Fragments of the exploding filament formed the core of a CME that raced away from the sun faster than a million mph: movie. NOAA analysts have modeled the trajectory of the CME and concluded that it will probably strike Earth's magnetic field on Nov. 8th. The impact could spark G1-class geomagnetic storms and auroras at high latitudes. Free: Aurora Alerts
AIRGLOW IN THE POLAR NIGHT: "Polar night is coming to the subarctic," reports Mia Stålnacke of Kiruna, Sweden, just inside the Arctic Circle. "The sun set at 2:36 p.m. yesterday and at around 7:30 p.m. I shot this."
Stålnacke's long exposure captured not only the Milky Way looming over Kiruna, but also a beautiful splash of green.
Inside the Arctic Circle, green is normally a sign of geomagnetic activity--that is, the aurora borealis. "But this was no aurora," she says. "It's airglow."
Airglow is a chemical reaction involving oxygen in the upper atmosphere driven in part by solar ultraviolet radiation and cosmic rays. Visibility waxes and wanes with conditions such as pressure and temperature in the rarified air more than 90 km above Earth's surface. Gravity waves traveling up from the planet below impress the verdant glow with a dramatic rippling structure.
Dark nights with a new or thin crescent Moon are the best times to catch a glimpse of airglow. Often, the glow is dim and pale to the naked eye, revealing its green color only to the lens of cameras set for Milky Way-length exposures. Seeing airglow above the Arctic Circle is even more challenging as it is frequently overwhelmed by the brighter glow of auroras. Stålnacke picked a rare night when auroras were absent. As her photo shows, however, the polar night is never truly free of wonders.
Realtime Airglow Photo Gallery
THE CANIGOU EFFECT: On the evening of Nov. 1st, J.P. Pettit watched the sunset from Marseille, France. As the fiery solar disk sank into the waters of the Mediterranean Sea, a jagged mountain thrust up in front of the sun ... "which is strange," says Pettit, "because there are no mountains sticking out of the Mediterranean." So he took this picture to document the apparition:
Indeed, there are no mountains in the Mediterranean, but there are mountains 165 miles away in the Pyrenees. "Pettit witnessed the 'Canigou Effect'," explains atmospheric optic expert Les Cowley. "This is the silhouette of the Pyrenees' Canigou Massif."
"There is no direct line of sight to the Massif because of the Earth's curvature," continues Cowley. "The view is only possible because light is refracted around Earth. Basically, the atmosphere is denser at lower levels and acts like a lens to bend sun rays around the horizon. Mirages can do the same thing, but a mirage was not needed here – just steady and clean air and a long stretch of sea."
"What an incredible special effect," says Pettit. "Just WOW!"
"This is not a chance observation," adds Cowley. "Alain Origne has made a systematic study of the phenomenon and predicts when it will occur. He would like to hear of other long distance sightings."
Realtime Space Weather Photo Gallery