The big sunspot cluster that created the auroras a few weeks ago is very likely just over the horizon on the sun, and it appears to have spat out a doozy of an X2.9 flare to announce its return. While we can’t see the sunspot cluster itself yet, astronomers estimate that it is the same angry AR3664 set that has been circling across the far side of the sun for the last two weeks. This hyperactive region launched the X class flares that produced auroras on May 10th that were so powerful they lit up the skies far from the poles in Florida and Queensland.
The solar storm was big enough that it reached down and twiddled with compasses on the sea floor as far as 2.7 kilometers (1.7 miles) underwater. So we are left with the paradox that solar weather controls half the groundwater refill in China, shows up in patterns of lightning in Japan, and somehow correlates with jellyfish plagues on Earth, but can’t possibly cause climate change. Apparently, our air conditioners can contribute to a heatwave but the vast electro-magnetic dynamo 333,000 times heavier than Earth can not. We know this because a foreign committee in Geneva says so, and they have skill-less models to prove it.
The global climate models agree that the effect of the solar-magnetic-wind and electric-field is exactly 0.0 degrees (per doubling of their NSF grants).
Some very active sunspots may last for months and each full rotation of the sun takes 27 days, so it may do a few laps and we may get more bites at this cherry. Or, if the sun is particularly grumpy, it may get more bites at us.
As the sun rotates we’ll see more of what is probably AR3664, though to confuse things, when it rolls over the horizon it will promptly get a new number-name. (It has and is now “AR13697”). It’s difficult to track what happens to every sunspot cluster as they travel across the far side of the sun, so all sunspots shifting into view are automatically given a new number. Though according to Daisy Dobrijevic at Space.com “scientists can track the sunspot’s progress across the sun’s far side by observing how it affects the sun’s vibrations or seismic echoes, using helioseismology data.” Sounds tricky. You’d think we’d have a camera on an asteroid on the far side recording the other half of sun, but we don’t. We spent $100 billion trying to blame a fertilizer for our storms, but a lot less than that trying to understand the sun.
As it happens, some officials at NASA even think the May aurora show was “one of the strongest auroras in 500 years”. They argue that some 7 different coronal mass ejections traveling at 3 million miles per hour, piled up together on the way and arrived all at once. In the last 70 years the other two big events were in 1958 and 2003. The Carrington event was so big it was seen in the Caribbean.
People who want to see an aurora may get lucky in the next two weeks if a flare is ejected in our direction
For those keen to see an aurora, look out for notices of a large X Class flares. Depending on how fast the ejections travel, the charged particles usually arrive here about two days later, but may come anytime from 15 hours to 4 or 5 days later. Once the particles hit the satellites at the Lagrange point the instruments give us about 15 to 45 minutes of warning. The Lagrange point is 1.5 million miles away from Earth towards the Sun in an area where gravitational and centripetal forces equal out, and it takes very little fuel for the satellites to maintain their position. It is the closest thing to a parking spot in space where our space-cars won’t roll away if we’re not looking.
Check the Glendale App for information or sign up for email alerts from the Australian Space Weather Forecasting Centre for aurora or from SpaceWeatherLive. Some bright spark set up Aurorasaurus to track aurora related tweets. Apparently they correlate quite well with geomagnetic indices. If only people were tweeting 150 years ago.
For the record: Solar flares are graded B, C, M and X class, with X being the largest and each grade putting out ten times more energy than the grade before. Within each grade there are nine log divisions (Eg. M1, M2 etc.) There is no upper limit on X class flares and the one in 2003 overloaded the instruments (which max out at X17). It was later estimated to be X45, which sounds like it could have eaten the earth. The flares in May were smaller, like X4.5 and X5.8 but conglomerate.
X class flares can trigger planet wide radio blackouts and potentially widespread auroras.
UPDATE: Auroras are a fickle tool for measuring solar activity as only the ones aligned the opposite way to Earths magnetic field will generate the color-show in the sky.
“The degree of magnetic disturbance from a CME [coronal mass ejection] depends on the CME’s magnetic field and Earth’s. If the CME’s magnetic field is aligned with Earth’s, pointing from south to north the CME will pass on by with little effect. However, if the CME is aligned in the opposite direction it can cause Earth’s magnetic field to be reorganized, triggering large geomagnetic storms. “ — Space.com
The direction of the solar wind interplanetary magnetic field is called the clock angle, and to see an aurora we need the “Bz” to be negative. Since the sun flips its own magnetic field with each cycle, perhaps one orientation is more likely to generate auroras than the other? Some Russians claim that “odd numbered” solar cycles are more exciting for aurora watchers (and this is an odd numbered cycle — number 25). It maybe no accident that the last big auroras were 21 years ago at the peak of the last solar maximum with the solar north pointed in the same direction as it is now. So get your fill now of auroras if you can. It may be 22 years between drinks, so to speak.
UPDATE #2: Sorry — thinking about it, the sun flips magnetic poles at solar maxima (ie. soon) not at solar minima but we label the “cycles” from solar minima to minima. Hence each 11 year Schwabe cycle will be half North-South, then the sun will flip to South-North for the second half. So it doesn’t necessarily follow that odd or even solar cycles will be better or worse for auroras. There is probably a 22 year pattern for auroras but it will be split across Schwabe cycles.
Thanks to Willie Soon.