THE FARSIDE OF THE SUN IS ACTIVE: Over the past week, three halo CMEs have exploded from the farside of the sun. Here is the latest on Dec. 15th. We can't see what's back there, but it is probably a large sunspot group crackling with activity. The sun's rotation will turn it toward Earth next week. Solar flare alerts: SMS Text
UNEXPECTED CME IMPACT: A CME was supposed to narrowly miss Earth today. Instead, it delivered a direct hit. The impact on Dec. 17th (0519 UT) sparked a G1-class geomagnetic storm with bright auroras over Alaska:
"The reds were fully visible to the eye!" says photographer Sacha Layos of Fairbanks, AK. "A complete treat for the eyes and soul."
The storm is over now and no more CMEs are expected to hit Earth this week. Famous last words? CME impact alerts: SMS Text
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POLAR STRATOSPHERIC CLOUDS OVER EUROPE: Polar stratospheric clouds (PSCs) are supposed to be confined inside the Arctic circle (hence "polar"). This week, they are spreading across Europe. Bernhard Edel saw them Dec. 16th from Vienna, Austria:
"The clouds were very colorful," says Edel.
PSCs are rare. Normally, the stratosphere has no clouds at all. When the temperature drops to -85 C, however, water molecules can get together to form ice crystals even in the very dry stratosphere. Sunlight touching those crystals creates a blossom of pastel color.
Clearly, the cold is spreading south. Vienna is at latitude +48 N. This means even mid-latitide observers should be alert for PSCs as the winter solstice approaches. You might even see them at night.
more images: from Alan C. Tough of Brodie Castle, Moray, Scotland; from Per Steinar Prøven of Brumunddal, Norway; from Ramune Sapailaite of Oslo, Norway; from Ramune Sapailaite of Gran, Norway
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