Right this moment, there’s an epic magnetic battle raging above our heads.
On Monday, at around 2 p.m. ET, a coronal mass ejection (CME) slammed into the Earth’s magnetosphere. According to NASA’s Space Weather Laboratory, the conditions were just right for the CME’s magnetic field to compress the Earth’s magnetosphere so much that, for a short time (between 3:06 p.m and 3:11 p.m. ET), energetic solar wind particles penetrated as deep as geosynchronous orbit — home to hundreds of communication satellites.
Although the interactions between solar plasma and Earth’s magnetic field are often invisible, tonight is an exception. Vast aurorae are rippling through the atmosphere at very low latitudes.
At time of writing, the US was being given a dazzling show as Spaceweather.com reports:
Northern Lights have spilled across the Canadian border into the contiguous USA. Sighting reports have come from as far south as Arkansas, Wisconsin, Michigan, Tennessee, Missouri, Illinois, Nebraska, Kentucky, Indiana, Oklahoma, Kansas, Maryland, New York, Ohio and central California.
Yes, central California! To see some of the auroral displays, the Universe Today has a few reader’s photos featured. My personal favorite is an earlier photograph taken in Norway.
Why is this happening? And why now?
It is well known that the sun is building in activity toward “solar maximum” — the peak is predicted to occur by around 2013 — and we have witnessed some huge solar flares recently.
Flaring activity and the eruption of CMEs are both symptomatic of the extreme magnetic stresses torturing the sun’s interior.
So, we’ve just experienced a CME punch — solar plasma contained within the CME and solar wind have streamed into the magnetosphere. Usually these energetic particles would follow the magnetic field lines and be confined to the North and South Polar Regions, creating the familiar Aurora Borealis and Aurora Australis, respectively — as the solar particles rain down through the atmosphere, impacts with atmospheric gases cause the atmosphere to glow. But this time the conditions were just right that the powerful CME impact caused a geomagnetic storm to ripple across the globe, extending the aurorae.
Scientists are able to measure when a geomagnetic storm is underway by using the “Kp index.” This measurement is derived by measuring how much the horizontal component of the Earth’s magnetic field varies over a 3-hour period. Depending on the intensity of fluctuations, the Kp index is assigned values between 0 to 9. If the value hits 5, this means a geomagnetic storm is occurring and auroral displays can be expected.
At its peak, the Kp index hit a “7” — a strong geomagnetic storm!
Apart from generating beautiful auroral displays at lower latitudes than would be expected, strong geomagnetic storms can have a sinister side. As energetic particles wash through our orbital neighborhood, vulnerable satellites can be damaged and huge electrical currents can be induced through the upper atmosphere, potentially overloading entire power grids.
Last year, the much-publicized “zombiesat” was caused by a solar storm knocking out a satellite’s ability to communicate with Earth. Its brains were, quite literally, “fried.”
And if you think it’s not possible for the sun to damage a power grid, think again. In 1989, Hydro-Québec power grid was knocked out by a geomagnetic storm caused by a CME hitting the Earth. Just before the grid was knocked out — leaving millions of customers without power for several hours — aurorae were spotted as far south as Texas.
It is unlikely that the current geomagnetic storm will cause satellite harm or power grid mayhem, but as society becomes ever more dependent on delicate electronics and constant mains electricity, we become increasingly vulnerable to the awesome violence of solar eruptions.
Leading Image: Space station astronauts watchan aurora snake across the Earth’s atmosphere from orbit on Sept. 17. Credit: NASA