Last month marked the two year anniversary of a strange astronomical close call for planet Earth.
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Last month marked the two year anniversary of a strange astronomical close call for planet Earth. On July 23, 2012, the largest solar flare in 150 years crossed Earth’s orbital path, but luckily, Earth was a week away from that spot in its orbit and the flare missed Earth entirely.
Even more luckily, the flare scored a direct hit NASA’s “STEREO A” satellite, which, among all of NASA’s satellites, was perhaps the best equipped to withstand and measure the flare, giving scientists an incredible opportunity to study the flare and estimate what effect it may have had on Earth. NASA’s STEREO mission is designed to study how Earth is affected by the sun’s activity. A pair of STEREO satellites lead and follow Earth continuously as it orbits the sun.
Solar flares can be thought of as explosions on the surface of the sun which release billions of tons of charged particles into space at a million miles an hour. The particles, if directed toward Earth, interact with and are partially deflected by our magnetic field and can interfere with satellites and communication systems. If they are strong enough, they can also interact with Earth’s surface and induce erratic magnetic fields on the ground which can have an effect on electrical infrastructure. For example, a solar flare in 1989 knocked out power to millions in Quebec for 9 hours.
In the two years since the flare, scientists have poured over the data from STEREO A and this past December wrote a detailed report on the findings. The flare turned out to have been more powerful than anyone fully realized at the time it occurred, and was the most powerful flare since the famous flare of 1859, called the “Carrington Event” (so named for an astronomer who happened to see the flare erupt from the sun’s surface). The Carrington Event in 1859 caused northern lights to be visible as far south as Cuba and induced magnetic fields on telegraph infrastructure; so much so, in fact, that it shocked telegraph operators and set some telegraph offices on fire.
A few years back, NASA sponsored a study done by the National Academy of Sciences which estimated the possible consequences of large solar storms on modern technology such as communications and electricity distribution systems. It estimated if the Carrington Event hit now it could have done $2 trillion of damage that could have taken years to fix.
Part of the reason the 2012 flare was so strong is that it was really two flares spaced around 10 minutes apart. A handful of flares that occurred a couple days before contributed by clearing a path to Earth allowing the double flare to cruise along more quickly than normal. These factors turned the 2012 flare into a sort of perfect solar storm.
This new information gives an incredible chance to have collected data on and studied such a large solar flare, and shows how important and valuable existing and new satellite instruments are to understanding and planning for events such as these. Had this flare happened before 2006, when the STEREO satellites were launched, we wouldn’t have been able to fully gauge these types of large solar storms in space and begin to plan for them. STEREO A even got video of the flare; you can see it by visiting www.nasa.gov and searching for “STEREO.”