What Causes Aurora?

By Nancy Atkinson - January 24, 2012 at 5:06 PM UTC | Physics

Will you be seeing an aurora tonight? Yesterday, January 23, 2012, an

M8.7-class flare erupted from the Sun

and sent a huge wave of high-energy protons towards Earth and Mars, moving at about 8 million kilometers per hour. According to

Spaceweather.com

, the CME hit Earth's magnetic field at approximately 1500 UT (10 am EST) today, and geomagnetic storms are likely in the hours ahead, as scientists say this the largest solar storm Earth has encountered since 2005.

But what is an aurora and what causes them?

Aurora are colorful lights in the night sky and primarily appear in Earth's polar regions. But what causes these colorful lights? (

See a gallery of aurorae from January 22-23

). When solar plasma is ejected from the Sun during a magnetic event like a flare or a coronal mass ejection, the plasma travels outward along with the solar wind and when it encounters Earth's magnetic field, it travels down the field lines that connect at the poles. Atoms in the plasma interacts with atoms in Earth's upper atmosphere, creating colorful dancing lights. Currently, with all the solar activity, lower than normal latitudes may see aurora.

Possible effects from the solar storm besides aurorae are power outages (geomagnetic storms can create electrical currents of hundreds of amps in long conductors on the ground, such as power transmission lines) and satellite damage, but both are very unlikely from this solar storm, which is not as powerful as the rather famous

"Halloween Storms of 2003,

" where the Solar and Heliospheric Observatory (SOHO) satellite failed temporarily and NASA's Advanced Composition Explorer (ACE) satellite experienced damage, and instruments aboard many spacecraft had to be shut down temporarily.

In A 1994 solar storm caused major malfunctions to two communications satellites, disrupting newspaper, network television and nationwide radio service throughout Canada. Other storms have affected systems ranging from cell phone service and TV signals to GPS systems and electrical power grids. In March 1989, a solar storm caused the Hydro-Quebec (Canada) power grid to go down for over nine hours, and the resulting damages and loss in revenue were estimated to be in the hundreds of millions of dollars.

Here's a look at yesterday's activity from three different spacecraft:

Nancy Atkinson

Nancy Atkinson

Nancy Atkinson is a space journalist and author with a passion for telling the stories of people involved in space exploration and astronomy. She is currently retired from daily writing, but worked at Universe Today for 20 years as a writer and editor. She also contributed articles to The Planetary Society, Ad Astra (National Space Society), New Scientist and many other online outlets.

Her 2019 book, "Eight Years to the Moon: The History of the Apollo Missions,” shares the untold stories of engineers and scientists who worked behind the scenes to make the Apollo program so successful, despite the daunting odds against it. Her first book “Incredible Stories From Space: A Behind-the-Scenes Look at the Missions Changing Our View of the Cosmos” (2016) tells the stories of 37 scientists and engineers that work on several current NASA robotic missions to explore the solar system and beyond.

Nancy is also a NASA/JPL Solar System Ambassador, and through this program, she has the opportunity to share her passion of space and astronomy with children and adults through presentations and programs. Nancy's personal website is nancyatkinson.com