From Adrien Mauduit at the Aurora observatory, Senja Island, Norway on March 17, 2019…
“It all started at around 10:00pm LT. Almost nothing until then when all of a sudden a big band appeared in the south. Around 10:30pm LT, a very nice show happened with some colorful and fast moving coronas.”
Adrien Mauduit is a visionary, an artist who captures the essence of Aurora in mesmerizing detail. Join me in appreciation of his vision by clicking on the link below and following Adrien Mauduit.
To the delight of Aurora watchers Earth’s magnetic field vibrates in protest of unrelenting solar wind. An Earth facing hole of monstrous proportion opened on the Sun, belching winds of 600 Km/second (that’s almost 1.2 mph ) toward our planet. Defensive vibrating twists in Earth’s magnetic field ignited powerful geomagnetic storms.
Astronomers predict intense aurora activity to continue for several days.
The current auroral oval commands the Northern Hemisphere. Anyone living under the oval owes it to themselves to look up under clear dark skies. Those lucky enough to meet Aurora, embrace her stamp of indelible wonder. She’s waiting – all you have to do is find her.
Beginning September 10, 1941 astronomers noticed a particularly active cluster of sunspots. Over the next week they blossomed, reaching magnitudes visible to the naked eye. For seven days the disturbance grew, drifting with solar rotation until they faced Earth. Seventy five years ago today they erupted, resulting in a solar event known as the geomagnetic blitz of 1941.
“A magnetic observatory in Cheltenham, Md., operated by the U.S. Coast and Geodetic Survey, registered six separate occurrences of geomagnetic storms with a K index of 9 (the most intense value possible). Five of these occurred consecutively over a 24-hour period. In terms of a related global index , the level of geomagnetic activity over a 24-hour period has not since been matched.”
An artistic graphic on sunspots that accompanied an informational story in The Plain Dealer’s syndicated “Uncle Ray’s Corner” column, published in the Illinois State Journal on 21 September 1941, a few days after a geomagnetic storm produced spectacular auroral displays. Credit: Plain Dealer Archive/Advance Media and State Journal Register
Assertive auroras danced from New Mexico to Chicago, New York and Washington DC. The Chicago Tribune wrote “a cosmic brush painted the Chicago sky with light”. Auroras across Europe were described by press in context of the war – illuminated by geomagnetic light, the British Royal Air Force bombed a German supply base on the Baltic Sea, and German forces stormed besieged Leningrad. Betrayed by aurora’s light, German aircraft attacked a convoy of Allied supply ships.
“Kapitänleutnant Eitel-Friedrich Kentrat of U-74 recorded the ensuing events in his war diary [Morgan and Taylor, 2011, pp. 119–123]: “September 18, 1941, visibility 4–6 nautical miles, a number of smoke plumes on the horizon, vessels seem well strung out.” Kentrat had spotted SC-44, a Canadian convoy of cargo ships. For protection, a destroyer and small antisubmarine warships known as corvettes escorted SC-44 along its journey.
At 22:30 UT, Kentrat issued a radio dispatch to headquarters and the other Brandenburg U-boats, “Alpha. Alpha. Enemy convoy in sight. Quadrant AD9761. Course NE, moderate speed. U-74.” Unsure whether his compatriots received his message, he recorded in his diary that since 04:30 UT on 18 September, “short-wave radio reception has been very poor and it gradually cuts out altogether. We try absolutely everything but without success. I hope the other Brandenburg boats can receive me.” Unbeknownst to Kentrat, his radio problems were caused by the magnetic storm and the ionospheric disturbance that followed.
As the Sun set, the sea haze lifted. Under such conditions, a wartime convoy would normally have been relatively securely hidden in the dark of night. But not this night. The sky was ablaze with the aurora borealis. Kentrat described the conditions as being “as bright as day.” Ironically, in a postwar interview [Johnston, 2008, p. 38], a crewman on board a ship in the convoy, the SC44 corvette HMCS Lévis, recalled seeing the aurora on that evening and remarking to a fellow crewman, “What a night for a torpedoing.” This bit of dark humor would turn out to be prophetic.
At 01:00 UT on 19 September, Kentrat tried several times to maneuver U-74 into attack position on the starboard side of the convoy, only to be “driven off” each time by SC-44’s defending corvettes. They didn’t pursue for long, but Kentrat became concerned that his own U-boat was too visible “in these conditions.” (In those days, submarines were only occasionally submerged.) He decided to maneuver “to the port side of the convoy, where the Northern Lights [were] less bright.”
At 03:50 UT, Kentrat radioed, “Brandenburg boats report in immediately.” (He did not know at the time that the other U-boats had been receiving his radio messages; he just hadn’t been receiving theirs.) At 05:03 UT, from the unusually long distance of 3 kilometers, Kentrat ordered four torpedoes fired in spread formation at the convoy. Afterward, U-74 quickly turned around to escape, and Kentrat ordered a fifth torpedo fired from the stern. Monitoring the results through his periscope, Kentrat reported a direct hit, “a plume” and “green light.” A torpedo had struck the stern of the Lévis, nearly cutting her in two. Afterward, Kentrat recorded detecting a desperate Morse code signal: “help.”
As I write tonight, solar winds unleashed from a wide Earth facing coronal hole are expected to reach Earth by September 20. Science predicts geomagnetic storms over the next few days. Other than brilliant high latitude auroras, it isn’t likely many will even notice. Nor is it likely a cautionary tale of the Geomagnetic Blitz of 1941 will register as anything but a page in history.
In my mind, space weather events are the least known, least taught and least acknowledged. I don’t get it. Over and over again, irrefutable accounts of solar assaults languish in obscurity.
To those not inclined, enthusiastic gushing over Earth poised to cross a fold in the heliospheric current sheet on April 29/30 likely falls flat. That’s OK, twenty years ago I wouldn’t have understood a solar sector boundary crossing meant geomagnetic storm. Living in a state of gob smacked wonder over auroras, didn’t equate to comprehending how or why – shreds of murky high school science were of little use. Solar dynamic’s light didn’t flicker until the day I decided to figure it out from the perspective of one without a formal science education.
In October 2014 I wrote a post titled “Solar Sector Boundary Crossing”. If I do say so myself – a concise, accessible, easily understood window to the wonder of solar dynamics.
“Hang on for a lesson in solar dynamics – Earth is experiencing a solar sector boundary crossing. Let me explain….
The sun produces wind (currently 410.9 Km/second) that blasts across the cosmos. Just like Earth, our Sun has a magnetic field – known as the interplanetary magnetic field (IMF). Whipped into a spiral rotation, wind driven IMF rotates in one direction. It divides into spiral sections pointing to and away from the sun along the ecliptic plane ( a direct line between Earth and the Sun). The edge of this swirling mass has a surface separating polarities of planetary and solar magnetism called the heliosphere current sheet.
Earth’s magnetic field points north at the magnetopause (the point of contact between our magnetosphere and the IMF). If the IMF happens to point south at contact (scientific term, southward Bz) the two fields link causing partial cancellation of Earth’s magnetic field – in other words, opening a temporary door for solar energy to enter our atmosphere. Welcome solar sector boundary crossing – a phenomenon born of high solar wind and coronal mass ejections (CME’s – aka solar flares).
It takes 3 or 4 days for magnetism to sort itself out – in the meantime, and barring the occasional high frequency radio disruption, wonky GPS and cell phones, peppered with sudden power grid failure events – we’re treated to kick ass auroras.”
SDO (Solar Dynamics Observatory) changed how we ponder our Sun. Launched on February 11, 2010, SDO became NASA’s first solar observatory. No larger than a minivan, purposeful and dedicated, SDO’s singular objective is to understand how solar activity impacts Earth. Instruments measure the Sun’s interior, magnetic field and plasma of the solar corona simultaneously – one mission, to understand space weather in relation to Earth and near-Earth space.
Space weather refers to the effects of solar wind on Earth’s magnetosphere, ionosphere and thermosphere. Conditions attributed to constant flows, punctuated by violent eruptions of solar plasma – charged particles, flung outwards from the Sun at speeds up to 1 million mph. Auroras, mesmerizing spectacles driven by clashes with solar plasma appear innocent enough – space weather has far greater ramifications.
Solar wind driven plasma is responsible for bending or obliterating radio waves, disrupting navigation systems, forcing airplanes to change course, decayed orbits of satellites, temporarily knocking out cell phone service and complete failure of power grids.During an intense geomagnetic storm in October of 2003, 46 0f 70 spacecraft failures were attributed to space weather. In March 1989, 3 minutes after impact of a severe solar storm, Quebec’s power grid was annihilated for 9 hours.
Over the next few weeks I’ll dissect space weather into digestible bites. Meanwhile, take a moment to witness one of SDO’s greatest gifts –
On June 21, NASA’s Solar and Heliospheric Observatory (SOHO) captured this image of coronal mass ejection (CME). NOAA forecasters immediately issued aurora and geomagnetic storm alerts. Predictions of a 90% chance it would “catch up”, joining forces with 2 weaker CME eruptions from June 18 and 19 didn’t disappoint. Yesterday an impressive G4-class magnetic storm ignited auroras deep below the Canadian border.
Not over yet, the second image illustrates “auroral oval” over tonight’s northern hemisphere sky. NOAA predicts a 90% chance of widespread aurora activity June 23, diminishing slightly to 70% on June 24.
Meanwhile, sunspot AR2371 produced an impressive M6.5 flare credited with shortwave and low-frequency radio blackouts over North America. Click on the spaceweather link to learn more.