Early this morning, people at southerly latitudes in the U.S. and elsewhere across the globe reported a fantastic display of northern lights seen during the night of October 24, 2011.
The northern lights – also called an aurora borealis – occurred after a coronal mass ejection (CME) from the sun struck Earth yesterday at approximately 18:00 UT (1:00 pm CDT) on October 24.
According to spaceweather.com:
The impact strongly compressed Earth’s magnetic field, directly exposing geosynchronous satellites to solar wind plasma, and sparked an intense geomagnetic storm. As night fell over North America, auroras spilled across the Canadian border into the contiguous United States.
Northern lights – typically a far northern latitude phenomenon – were seen as far south as Nebraska, Arkansas, Tennessee, northern Mississippi, Alabama, North Carolina and Virginia.
Spaceweather.com also reported the phenomenon of the red aurora, which occurs with a particularly direct and powerful hit from a CME from the sun:
Many observers, especially in the Deep South, commented on the pure red color of the lights they saw. These rare all-red auroras sometimes appear during intense geomagnetic storms. They occur some 300 to 500 km above Earth’s surface and are not yet fully understood.
Will you see the northern lights on the night of October 25? Maybe. These displays sometimes last more than a day. Woot! However, the storm is diminishing now. It’s doubtful that those at southerly latitudes will see another display tonight as glorious as the one last night. But those in the northern U.S. or Canada – or similar latitudes – should watch for northern lights tonight as Earth’s magnetic field continues to react to the CME impact. Plus, as always, the only way to know is to look!
What caused such a strong display of the northern lights? A coronal mass ejection (CME) shot off the sun late in the evening of October 21, 2011. This material from the sun struck Earth on October 24 at approximately 18:00 UT (1:00 pm CDT) on October 24. The CME caused strong magnetic field fluctuations near Earth’s surface, resulting in a beautiful aurora that could be seen as far south as the southern U.S.
NASA’s SOlar Heliospheric Observatory (SOHO) captured the “coronograph” – above – of the October 21 CME. In this image, the sun itself is blocked out, and you’re seeing only the sun’s atmosphere or corona. The CME that caused the aurora to appear on the evening of October 24 begins when the counter in the lower left reaches October 22, 1:36 (which translates to October 21, 8:36 PM CDT).
NASA says the October 24 CME had such strength, speed, and mass as it struck Earth that it pushed the boundary of Earth’s magnetic fields – a boundary known as the magnetopause – from its normal position at about 40,000 miles away from Earth inward to about 26,000 miles. This is the area where spacecraft in geosynchronous orbit reside, so these spacecraft were briefly orbiting outside of Earth’s normal environment, traveling through material and magnetic fields far different from usual.
Did you see the northern lights last night? Post your image on EarthSky’s Facebook page!
Bottom line: Check out the buzz on the Internet today about the great display of northern lights over North America – seen even into southerly latitudes – last night (October 24).