Just in time for Valentine’s Day, [and the Stardust flyby of Comet Tempel 1] the Sun erupted with a massive X-Class flare, the most powerful of all solar events on February 14 at 8:56 p.m. EST . This was the first X-Class flare in Solar Cycle 24 and the most powerful X-ray flare in more than four years.
The gif above shows the flare as imaged by the AIA instrument at 304 Angstroms on NASA’s Solar Dynamics Observatory.
Video caption: The X2 flare of Feb. 15, 2011 seen by SDO (in extreme ultraviolet light) enlarged and superimposed on SOHO’s coronagraph that shows the faint edge of a “halo” coronal mass ejection as it races away from the Sun. The video covers about 11 hours.
A CME hit Earth’s magnetic field at approximately 0100 UT on Feb. 18th (8:00 pm EST on Feb. 17th). Space weather experts predicted that jets of charged particles smacking into the Earth’s magnetic field could disrupt navigation and communication systems, and spark a bonus of bright northern lights dancing across the ionosphere.
Instead, nothing much happened.
“There were some nice displays of aurora, but you had to live in the northernmost or southernmost part of the globe to see them.
The storm was so weak because the flare’s magnetic field happened to be aligned parallel to the Earth’s. When the sun sends a mass of hot plasma hurtling toward the planet in a coronal mass ejection, the plasma is imprinted with its own magnetic field separate from the sun’s. Astronomers can’t predict the direction of the plasma’s magnetic field until the burst hits Earth.
If the plasma’s magnetic field is parallel to the Earth’s, the incoming charged particles are effectively blocked from entering Earth’s magnetosphere. An identical flare with a perpendicular magnetic field would have triggered a much stronger storm.
“If the magnetic fields are parallel, then the shields are up. We are well protected,” said space weather expert Juha-Pekka Luntama of the European Space Agency Feb. 19 at the meeting of the American Association for the Advancement of Science in Washington, DC.
But next time we might not be as lucky with alignment, and we can expect up to 1,700 more storms like last week’s in the coming months as the sun wakes back up.
- Sun Erupts with Enormous X2 Solar Flare
- NASA Video Gallery: The Sun – Feb. 15-16, 2011
- Giant Solar Blast Headed for Earth