From: Anne Assaff [mailto:anne.assaff@yahoo.com]
Sent: April-17-15 11:33 AM
Subject: Northern Lights last night
The auroras were visible late last night. To the naked eye, they looked like faint colourless curtains with shafts of light or “pillars” appearing occasionally. But with a 30 second exposure on the camera, the vibrant colours showed up. (My camera doesn’t handle high ISO very well, so I had to apply a noise-reduction filter after.)
I found this interesting explanation on the colours:
“The most common auroral color, a pale yellowish-green, is produced by oxygen molecules located about 60 miles above the earth. Rare, all-red auroras are produced by high-altitude oxygen, at heights of up to 200 miles.” (from northernlightscentre.ca)
Unfortunately, there isn’t much warning when aurora are forecast. This is a good site to check http://www.swpc.noaa.gov/products/30-minute-aurora-forecast
Anne
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