St. Patrick's Day Aurora Photos: Geomagnetic Storm Leads To Spectacular Northern Lights

The cosmos aligned to deliver a spectacular green light show for St. Patrick's Day. Two coronal mass ejections (CME) on Sunday led to a severe G4 geomagnetic storm and aurorean displays on Tuesday. Amateur astronomers and stargazers in the Northern Hemisphere were treated to a spectacular green and purple display across the night sky.

A CME is plasma (i.e., superheated matter with its own magnetic field) hurled from the sun. When the charged particles hit Earth's Northern Hemisphere, they sometimes trigger a geomagnetic storm that can affect power grids, cause radio blackouts, disrupt navigation systems and create auroral activity in the as far south as Alabama. Sunday's CMEs grazed Earth on Tuesday and triggered a G4 geomagnetic storm on the National Oceanic and Atmospheric Administration's space weather scale. Despite the severity, no damage to satellite equipment or power grids was reported.

The geomagnetic storm began at 10 a.m. EDT on Tuesday and was not accompanied by a radiation storm, Thomas Berger, director of the Space Weather Prediction Center, said during a press briefing. SWPC did not report any damage associated with the geomagnetic storm but predicted the effects of the CME to continue for 24 to 36 hours.

"G2 (moderate) geomagnetic storm levels continue as CME effects persists. G2 level storms are expected, with the potential for G3 (strong) storm levels through 18/0200 EDT (18/0600 UTC). Conditions should begin to settle down by early morning (EDT) as CME effects wane, however the potential for G1 (minor) conditions will persist through 18/1200 UTC (0800 EDT on 18 Mar)," SWPC said in a Facebook post Wednesday.

While Tuesday's geomagnetic storm caused a pretty light show, CMEs could have a huge impact on Earth. On July 2012, the planet dodged a powerful CME that could have triggered a severe storm. Researchers estimate the storm would have led to $2 trillion in damages. "If it had hit, we would still be picking up the pieces," Daniel Baker, from the University of Colorado, said in a statement.

Jeff Wallace witnessed the aurora from Alberta, Canada and captured purple and green Northern Lights. "This image was taken about an hour after sunset, and the purples were still strong. Purple light is emitted from nitrogen gas in our atmosphere when the plasma from the sun collides with our atmosphere. Oxygen emits green light," Wallace said.

Slooh was on hand in Iceland to view the Northern Lights. You can view highlights of the St. Patrick's Day aurora broadcast below.