FIRST DAY OF NORTHERN AUTUMN: The seasons are changing. Today, Sept. 22nd at 10:49 a.m. EDT, the sun crosses the celestial equator heading north. This marks the beginning of autumn in the northern hemisphere and spring in the southern hemisphere. At this time of year, day and night are of nearly equal length, hence the name "equinox" (equal night).
AUTUMN LIGHTS: The onset of northern autumn means it's aurora season. For reasons researchers don't fully understand, equinoxes are the best times to see Northern Lights. Right on cue, the Arctic Circle is glowing. Tom Eklund sends this picture taken Sept. 20th from Akaa, Finland:
"This was one nice auroral event--maybe the best display so far during this solar cycle!" says Eklund. "The vivid green belts with their pink lower edges were breaktaking."
The show's not over. A solar wind stream is expected to hit Earth's magnetic field this weekend, sparking more fall colors around the Arctic Circle. Aurora alerts: text, voice.
SEASON IN A BEER CAN: Jan Koeman of the Netherlands has captured an entire season in a single beer can. On June 21st, Koeman assembled a solargraph--a simple pinhole camera consisting of a beer can lined with photographic paper--and throughout the summer of 2012 he used it to record the sun's daily motion across the Dutch sky. Yesterday, Sept. 21st, he removed the photo-paper for inspection:
"As you can see, the summer wasn't too bad at all!" says Koeman. "There was l ots of sunshine in the backgarden of my parents in Middelburg."
Next up: Autumn in a beer can. Stay tuned.
Solargraph How-to Guides: #1, #2, #3
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Solar wind
X-ray Solar Flares
Daily Sun: 22 Sep 12
Solar activity is low. None of these sunspots is actively flaring. Credit: SDO/HMI
Sunspot number: 74
Current Auroral Oval: 
Switch to: Europe, USA, New Zealand, Antarctica
Planetary K-index
Interplanetary Mag. Field
Coronal Holes: 22 Sep 12
A solar wind stream flowing from the indicated coronal hole should reach Earth on Sept 22-23. Credit: SDO/AIA |
