THE SOLAR WIND HAS ARRIVED: Earth is entering a stream of high speed (> 500 km/s) solar wind flowing from a canyon-shaped hole in the sun's atmosphere. This could cause minor G1-class geomagnetic storms and auroras around the Arctic Circle. Aurora alerts: SMS Text.

LUNAR OCCULTATION OF MARS: Last night, the full Moon passed directly in front of Mars, producing a rare lunar occultation visible across North America and Europe. Matthew Melnyk of Calgary, Alberta, photographed the Red Planet moments before it disappeared:

"I was able to watch Mars as it passed behind the full Moon," says Melnyk. "It was very fun to watch through the zoom lens!"

The occultation was unusual in part because it occurred within a week of Mars's closest approach to Earth. The disk of the Red Planet was unusually wide, and it shone with a brightness greater than any star in the sky. During the occultation, Mars was twice as bright as Sirius, allowing people to see and photograph the planet even when it was very close to the edge of the glaring Moon.

Timothy Printy of Manchester, New Hampshire, caught Mars half-in and half-out of eclipse by a range of lunar mountains:

"Mars was just emerging from behind the Moon when I managed to get this image using my Meade 10-inch telescope and a Nikon D7200 camera," says Printy. The exquisite timing required a fast exposure--"only 1/80th of a second at ISO 800."

Got a picture of the occultation? Submit it here.

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AURORAS IN THE AFTERNOON: Yesterday, Dec. 7th, a co-rotating interaction region (CIR) hit Earth's magnetic field. The resulting auroras were so bright, they were visible in afternoon twilight over Utsjoki, Finland:

"It's polar night here at around 70°N in the far north of Finnish Lapland," says photographer Rayann Elzein. "It becomes night at around 3 pm, and that's when the CIR arrived. Despite a bit of remaining twilight and the almost full Moon, the sky was filled with green but mostly purple auroras! What a night ... or should I say afternoon?"

CIRs are transition zones between streams of fast and slow solar wind. They contain shock waves that can spark geomagnetic storms. Yesterday's CIR caused a G1-class storm that lasted several hours starting around 1300 UT.

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