ARCTIC AURORAS: A minor stream of solar wind is buffeting Earth's magnetic field today, Dec. 17th, and this is causing intermittent auroras around the Arctic Circle. "It may be Solar Minimum, and there may be a bright Moon hanging in the sky, but the Northern Lights are still shining strong and bringing a smile to everyone in our small village!" reports Chad Blakley from Abisko National Park in Sweden. "Check our webcam for updates." Free: Aurora Alerts.
WEEKEND COMET FLYBY: Over the weekend, Comet 46P/Wirtanen made history. The green ball of gas wrapped around a nugget of dirty ice flew past Earth only 11.5 million km away--so close that it cracked the top 10 list of comet flybys during the Space Age. During the hours of closest approach, 46P/Wirtanen appeared in the constellation Taurus alongside the Pleiades star cluster:
Michael Jäger took the picture on Dec. 16th from Turmkogel, Austria. "To create the image, I combined 6-minute exposures through red, green and blue filters," says Jäger.
The colors in Jäger's image are remarkable--a striking contrast of green vs. blue. Wirtanen's green comes from diatomic carbon (C2)--a gaseous substance common in comet atmospheres that glows green in the near-vacuum of space. The Pleiades, on the other hand, appear blue because the stars themselves are that color. Hot and massive, the Seven Sisters shine their blue light into surrounding clouds of gas and dust, which reflect the azure hue.
46P/Wirtanen is receding from Earth now, but it will still be nearby for days to come. The main challenge for observers is not distance, but rather moonlight. The glare of the waxing Moon will dilute the comet's brightness, making it a challenge to see with the unaided eye. Digital cameras and widefield telescopes will have no trouble, however, capturing the comet's exit. It is currently glowing like a big misty star of 4th magnitude near the horns of the Bull:
Got a picture of 46P/Wirtanen? Submit it to Spaceweather.com's Realtime Comet 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:
Every item in the Earth to Sky Store has flown to the stratosphere alongside an array of cosmic ray sensors. Carried aloft by giant balloons, these unique gifts travel above 99.7% of Earth's atmosphere, experiencing space-like blasts of cosmic rays, extreme cold, and a wild ride parachuting back to Earth after the balloon explodes. Even Amazon doesn't carry items this far out!
Don't forget to enter coupon code "SPACESANTA" at checkout for a 10% holiday discount.
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