VENUS-SATURN CONJUNCTION: When the sun goes down tonight, step outside and look southwest. Venus and Saturn are converging for a sunset conjunction. At closest approach on Dec. 11th, the two planets will be just under 2 degrees apart. Brilliant Venus pops out of the twilight first, followed ~15 minutes later by 1st-magnitude Saturn. Full story.
AN OUTBURST OF SOLSTICE AURORAS: Auroras love equinoxes. Solstices? Not so much. A 75 year study shows that December is the worst month for geomagnetic activity. At this time of year auroras tend to subside. But they never vanish, as shown in this photo taken by Markus Varik of Tromsø, Norway, on Dec. 6th:
"Northern Lights are less for sure around solstices, but this display was bonkers," says Varik, a longtime aurora tour guide who has experienced many Decembers inside the Arctic Circle. "What a wonderful night!"
Auroras prefer equinoxes because of the Russell-McPherron Effect. In September and March (equinoxes), cracks open in Earth's magnetic field. Solar wind pours in to fuel geomagnetic activity. In December and June (solstices), those cracks tend to close. It's ironic, but Northern Lights do retreat during the longest darkest nights of the year.
"Despite the 'solstice problem', we still get some good displays during December," assures Varik. The next opportunity is just days away. On Dec. 14th a stream of solar wind flowing from a southern hole in the sun's atmosphere is expected to graze Earth. Arctic sky watchers should be alert for auroras mixed with moonlight.
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THE NORTHERN LIGHTS PENDANT: On Dec. 6, 2019, the students of Earth to Sky Calculus launched a cosmic ray balloon to the stratosphere. This Northern Lights pendant went along for the ride, flying more than 107,612 feet above the rugged Sierra Nevada mountains of central California:
You can have it for $119.95. The students are selling these pendants to support their cosmic ray ballooning program. Each one comes with a greeting card showing the pendant in flight and telling the story of its journey to the edge of space. It makes an out-of-this-world Christmas gift!
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