The above picture, taken with the DES satellite on March 13, 1989 during a Great Aurora, shows that some aurora can be seen very far south. The southern edge of this auroral oval extended to the Great Lakes and could be seen almost directly over head. Further south, in Florida, observers saw a bright red glow in the northern horizon, but close to the horizon.
Aurora are commonly seen only at latitudes near 60 degrees, however, a few rare aurora have been seen near the equator, like the 1909 storm seen in Japan. The reason they don’t happen in the equatorial regions is that the flows of energetic electrons and protons that trigger aurora travel along magnetic field lines that connect the distant geomagnetic tail region with the Earth’s surface field. These field lines reach the Earth only in the polar cap areas. In the equatorial zone, the only field lines there connect the two poles via magnetic field lines that are much closer to the Earth and do not each out into the geotail. Some aurora, during exceptional geomagnetic and solar storms, are seen in the equatorial zone, but not very close to the zenith. You still have to look directly north or south to see the auroral glow, so they are still a product of geotail ‘field aligned’ current flows, although over a greatly expanded range of magnetic field lines.
It has been over a year since I published my book on how to build DIY magnetometers that can detect geomagnetic storms. The $8.00 B/W book ‘Exploring Space Weather with DIY Magnetometers‘, is available at Amazon by clicking [HERE]. It contains 146 pages with 116 illustrations and figures that describe six different magnetometers that you can build step-by-step for under $50.00.
Over the last year I have posted at my Astronomy Cafe blog, and at various LinkedIn groups, the magnetograms from my most sensitive magnetometers to show how well they capture the rapid changes of Earth’s magnetic field during a geomagnetic storm. Since I started posting these DIY magnetograms on Linkedin, they have received over 13,500 views so there seem to be a lot of teachers, amateur astronomers and space weather enthusiasts interested in my DIY technology.
On the NOAA Scale, these storms are stronger than G2 and are currently happening every month or so during the sunspot-maximum period. This blog is my Gallery of the storms I have detected so far. I also show the data for each storm event observed from the Fredericksburg Magnetic Observatory (FRD) located about 200 miles south of my suburban Maryland location. This will give you a sense of just how accurate my designs are compared to the far more expensive, professional-grade systems.
By the way, the July 14, 2023 magnetogram ‘spots’ shows what can be accomplished by a simple $5.00 soda bottle magnetometer if you follow a design with a laser pointer and a 7-meter projection distance as described in my book.
Ok…so here are the magnetograms in reverse chronological order starting from the most recent storms and working down the list to the earlier ones towards the end of 2023. I am only presenting the magnetograms and not a lot of supporting information about the circumstances of the storms themselves. For this information, visit the Spaceweather.com website and in the upper right corner of the webpage in the Archive area enter the date of the storm and you will be able to see a lot of info and even amateur photos of the resulting aurora themselves.
October 10-12, 2024, Major Kp=8-9, Great Aurora. FRD magnetic observatory plot (red) versus the RM3100 (black). Single-digit Kp index numbers on top row (from 2 to 9). The features that look like sudden ‘glitches’ at Kp=9, 8 and 7 seem to be very real and rapid changes in the D-component (angular displacement). 1000 units on the vertical axis corresponds to 200 arcseconds or 3.3-arcminutes variation.
August 12, 2024. Major Kp=8 storm. Green arrows are the Sq current variations. FRD (red) and RM3100 (black).
August 2, 2024 Kp=7 storm event. FRD(black) and RM3100 (blue).
June 23, 2024, Kp=8. Sq minima (arrows). Storm event (blue bar).
May 12, 2024, Kp=6 storm. FRD(red), RM3100 (black), Photo (blue), Hall (green).
May 10, 2024 Kp=8-9 major geomagnetic storm.
May 5, 2024 storm Kp=4-5. FRD(red), RM3100 (black)
March 23, 2024. Diurnal Sq dips (arrows) and a strong geomagnetic storm (hour 40). FRD data (red) and RM3100 data (black).
November 27, 2023. Minor Kp=6 storm at running UT of 83-86 . FRD data (yellow), RM3100 (grey), photoelectric magnetometer (orange), Hall sensor (blue)
November 5, 2023. A significant Kp=7 geomagnetic storm superposed on a few wobbles due to Sq current effects.
October 30, 2023. Three days of Sq variations and no geomagnetic storms. FRD data (red), RM3100 magnetometer (black), photoelectric magnetometer (blue), Hall effect magnetometer (orange).
July 14, 2023. Kp=4 geomagnetic storm (blue bar) with three cycles (yellow) of the diurnal Sq current. Red line = FRD data. Spots = soda bottle magnetometer.
We had a minor geomagnetic storm on Monday just after the major storm on Saturday that everyone saw. This minor storm launched a CME caused by an X-5.8 solar flare on Friday, but despite early estimates it might rival the major storm, it was a glancing blow to Earth’s magnetic field and caused no aurora over much of the Lower-48 States. Many had hoped they would get to see an aurora in Maryland and other mid-latitude locations but the storm was too week to be seen in most states that had enjoyed the Great Storm of May 10-11.
Nevertheless, my DIY magnetometers did show some life for this Kp=6 event as shown below. This time I had three different magnetometers operating. The top numbers are the 3-hour Kp indices. The red trace is from the Fredricksberg Magnetic Observatory. The black trace is from the RM3100-Arduino system. The blue trace is from the Differential Hall Sensoe system. The green trace os from the Differential Photocell Magnetometer. The two dips marked with ‘Sq’ are the diurnal Sq variations, which were recorded by all magnetometers.
We just passed through the biggest ‘solar storm’ in the last 20 years caused by the massive naked-eye sunspot group called AR-3664. Its size was 15 times the diameter of Earth and rivaled the size of the famous Carrington sunspot of September, 1859. Since it first appeared on May 2, it remained inactive until May 9 when it released an X2.2-class solar flare at 10:10 UT.
This enormous and violent release of energy stimulated the launch of six coronal mass ejections of which three merged to become an intense ‘cannibal CME’ that arrived near Earth on May 10 at 16:45 UT. Its south-directed magnetic field was perfect for imparting the maximum amount of energy to our planet’s magnetosphere. For a transit time of about 24-hours, it was traveling at a speed of about 1,700 km/s when it arrived. It sparked a G5-level extreme geomagnetic disturbance with a Kp index of 9 between May 10, 21:00 UT and May 11, 03:00 UT.
On May 9th at 06:54 UT AR-3664 produced an X-3.9 flare. This was followed on May 11 with a fourth major X-5.8 flare at 1:39 UT, which caused an immediate shortwave radio blackout across the entire Pacific Ocean that lasted for several hours. It is expected that the May 11 flare sparked anoher CME that may arrive near Earth on Monday evening May 13.
The last G5 geomagnetic storm that we experienced was way back in October 28 to November 5, 2003. These Halloween Storms caused power outages in Sweden and damaged transformers in South Africa. Despite many recent cautionary comments in the news media about cellphone and satellite outages and power grid problems, as yet none of these have been identified but perhaps in the next few weeks these technological impacts may start to be mentioned as anecdotes begin to surface.
Unfortunately, many areas on the East Coast were covered by clouds during this three-day period and missed the opportunity to see these major aurorae. However, my DIY magnetometer (see my earlier blog on how to build your own $50 magnetometer (located in Kensington, Maryland (latitude 39o N) was able to keep up with the invisible changes going on, and produced a very respectable record of this entire storm period. As a scientist, I am often working with things I cannot directly see with my eyes, so the fact that I had my trusty magnetometer to reveal these invisible changes around me was pretty cool!
This graph shows a side-by-side comparison of the data recorded by my RM3100 magnetometer (black) and the magnetometer at the Fredericksberg Magnetic Observatory (red). I have shifted and rescaled the plots so you can more easily see how similar they are. This is very satisfying because it shows that even a simple home-made magnetometer can perform very well in keeping up with the minute changes in the geomagnetic field. This plot shows the variation in the so-called D component, which is the local magnetic declination angle. Mathematically is is defined by D = arctan(Bx/By). It’s the angle relative to geographic North that your local compass points.
Below is a slightly different graph of the RM3100 data. As you can see in the first part of the above plot between 36 and 63 UT hours, the smooth change is caused by the diurnal Sq current effect that is correlated with the solar elevation angle. During this storm period, it is assumed to have behaved smoothly during the actual storm, so in the graph below I have subtracted it from the magnetometer data. The result is that I have now isolated the changes due to the storm itself. The top row of numbers are the 3-hour Kp index averages from NOAA. The marked times are for EDT in Maryland. Universal Time is 4 hours ahead of EDT.
This was, indeed, a very powerful storm that lasted about 42 hours. This places it among a handful of exceptional geomagnetic storms that includes the great Carrington Storm of August 28 to Septemer 5, 1859.
Why is this important? Well, in the grand scheme of things it may not matter much, but as an astronomer it is still a lot of fun to have access to the invisible universe from the comfort of my suburban home. I will let geophysicists have all the fun deciphering all the bumps and wiggles and what they tell us about our magnetic field and solar storms!
Meanwhile, my gear is primed and ready to go to detect this Monday’s next storm. Some predict that it may be even bigger then the one we just experienced. It’s interesting how the Carrington Storm was actually two major storms separated by a few days, with the CME from the first storm also canibalizing several other CMEs that were also enroute.
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