GEOMAGNETIC UNREST PREDICTED: A shallow hole in the sun's atmosphere is facing Earth, spewing a minor stream of solar wind toward our planet. Polar geomagnetic unrest is likely when the gaseous material arrives on Dec. 16th. This event will probably not rise to the level of a geomagnetic storm, but could spark Arctic auroras anyway. Free: Aurora Alerts.
METEORS FROM A ROCK COMET: The annual Geminid meteor shower is peaking today, Dec. 14th, as Earth passes through a gravelly stream of debris from rock comet 3200 Phaethon. Observers with the International Meteor Organization are reporting more than 85 meteors per hour. Amirreza Kamkar photographed this bright Geminid streaking over the Lut Desert in Kerman, Iran:
On the night of Dec. 13th, I was taking nightscape images in the Lut Desert, a natural World Heritage site located near Kerman, Iran," says Kamkar. "As moonlight illuminated the scene, making shadows in the foreground, a Geminid cut through the sky overhead. It was like being in a science fiction movie!"
Geminid meteors may be seen at any time of night, but the best time is during the hours before dawn when the constellation Gemini is high in the sky. Orient yourself using this sky map.
CHRISTMAS COMET WIRTANEN: Comet 46P/Wirtanen is approaching Earth for an historic encounter on Dec. 16th--one of the 10 closest comet flybys of the Space Age. Some people are calling it the "Christmas Comet." Indeed, it seems to be an excellent tree-topper:
"I took this picture from the forest outside Bleikvassli, Norway, on Dec. 12th" says photographer Tommy Eliassen. "The comet is in the constellation Taurus, which I positioned behind a tall tree for this Christmas composition."
Although the comet is coming very close to Earth, it is not very bright. Wirtanen's icy nucleus is small (~1 km) compared to greater comets such as Hale-Bopp (~30 km) and Halley (~15 km). At the moment it is glowing like a 4th magnitude star, barely visible to the unaided eye.
Now for the good news: This comet is an easy target for digital cameras with exposures as short as 10 to 30 seconds. Astrophotographer Juan Carlos Casado offers some advice to novices: "Use Raw file format, a fast lens (at least f/2.8) and ISO settings between 1600 and 3200. The exposure will depend on the focal length. I normally use the 500 rule–that is, exposure = 500 / focal length (mm). It also helps in areas with light pollution to use an antipollution filter. I am now using Optolong L-Pro clip filter which gives excellent color balance."
On the nights of closest approach, 46P/Wirtanen can be found in the constellation Taurus high in the sky before midnight. Sky watchers in the northern hemisphere may orient themselves using these sky maps: Dec. 14, Dec. 15, Dec. 16
Realtime Space Weather Photo Gallery
CHRISTMAS GIFTS FROM THE EDGE OF SPACE: So far in 2018, the students of Earth to Sky Calculus have launched 42 space weather balloons to the stratosphere, measuring cosmic rays over 3 continents, 2 hemispheres, and 7 different US states. You can help them pay their helium bill by purchasing a Christmas gift from the edge of space:
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