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Daily Suspicious0bserver's Weather Post:
September 22, 2014

What's in the sky tonight?
September 22, 2014

-NOAA forecasters estimate a 30% chance of polar geomagnetic storms on Sept. 23-24 when a co-rotating interaction region (CIR) is expected to hit Earth's magnetic field. CIRs are transition zones between fast- and slow-moving solar wind streams. Solar wind plasma piles up in these regions, producing density gradients and shock waves that do a good job of sparking auroras.

-The northern autumnal equinox is less than a day away. That's good news for sky watchers because, for reasons researchers do not fully understand, auroras love equinoxes. At this time of year even gentle gusts of solar wind can spark a nice display of Northern Lights. Igor Matveev took the picture on Sept. 19th from Monchegorsk, Russia. There was no geomagnetic storm predicted that night--and no meteor shower. Yet Matveev saw both. "What luck!" he says. "I caught the entire meteor streaking beneath the auroras."

No CME was required to spark the auroras. Instead, a relatively minor fluctuation in the magnetism of the solar wind caused the display. Tomorrow's CIR (co-rotating interaction region), explained above, could be even more effective.

Astro Picture of the Day:
September 22, 2014

Source:
Earth is at equinox. Over the next 24 hours, day and night have nearly equal duration all over planet Earth. Technically, equinox transpires at 2:29 am Universal Time tomorrow, but this occurs today in North and South America. This September equinox signal that winter is approaching in the northern hemisphere, and summer is approaching in the south. At equinox, the dividing line between the sunlit half of Earth and the nighttime half of Earth temporarily passes through Earth's north and south spin poles. This dividing line is shown in clear detail in the featured video, taken by the Russian meteorological satellite Elektro-L during last year's September equinox. The Elektro-L satellite is in geostationary orbit over one spot on Earth's equator and always points directly toward the Earth. The featured video shows a time lapse for an entire day surrounding the equinox, with a new image taken every 30 minutes. Cloud motions are visible as well as the reflection of the Sun are visible as the equinox day progressed. The next Earth equinox is scheduled for March.