HAPPY EQUINOX: Autumn begins in the Northern Hemisphere, and spring in the Southern Hemisphere, today at 4:02 p.m. EDT. That's when the sun crosses the equator heading south for the season. Astronomers call this date the equinox, because night and day are of almost equal length. It also marks the beginning of aurora season. Data prove it: Auroras love equinoxes. At this time of year, even a gentle gust of solar wind can spark a bright display. Free: Aurora Alerts
THE LAST DAY OF SUMMER IN NORWAY: The onset of autumn around the Arctic Circle brings an end to relentless summer sunlight--and a new beginning for Northern Lights. Frank Olsen of Andøya island, Norway, witnessed both on Sept. 21st:
"Last night brought an amazing sunset," says Olsen. "Its glow lasted for hours. A slow-moving aurora band completed the scene with its promise of the season ahead."
That promise could be fulfilled very soon. A solar wind stream flowing from a hole in the sun's atmosphere is heading for Earth. Estimated time of arrival: Sept.23rd or 24th. NOAA forecasters estimate a 40% chance of polar geomagnetic storms when the solar wind arrives. Free: Aurora Alerts