Tonight into tomorrow, northern hemisphere sky watchers as far south as Iowa or Michigan to Washington State are on aurora alert. Auroras are caused by charged particles hitching a ride on solar wind, dark skies turn undulating curtains of mischievous colour when charged particles interact with molecules in our atmosphere. Usually, our magnetosphere acts as a planetary shield preventing geomagnetic interaction of charged particles. Every so often fast moving particles overwhelm our magnetic field, create an opening and light up night skies.
On May 12, a magnetic filament on the sun, seen here, became unstable and erupted. (NASA/SDO)
Since Monday, 3 additional solar eruptions sent fast moving charged particles our way. As a result the auroral oval (doughnut shaped ring around the pole where charged particles follow magnetic field lines, reason why far northern latitudes regularly witness geomagnetic storms), has shifted far to the south.
The northern lights as seen looking eastward from just east of Penzance, Sask., at 1:21 a.m. local time Tuesday morning. (Submitted by Notanee Bourassa)
The colour of that light depends on the kind of molecule and the altitude of the collision.
Green is the most common colour, produced when the particles collide with oxygen at an altitude of around 100 to 300 km. At about 300 to 400 km, the interaction with oxygen produces red. Pink occurs below 100 km when nitrogen atoms are struck.
Bottom line – Space Weather Prediction Centre forecasters say there’s a 75% chance of geomagnetic storm activity tonight. If your skies are clear, go outside. If she’s willing, Aurora will find you. Opportunities like this don’t come along every day.
On April 5 NASA scientists launched sounding rocket mission AZURE (Auroral Zone Upwelling Rocket Experiment) from Norway’s Andoya Space Center. Twin rockets deployed chemical tracers capable of allowing researchers to track the flow of neutral and charged particles during an active geomagnetic storm. Emergency service switchboards were inundated with UFO sighting hysteria – seems no one bothered to alert residents of AZURE’s chemical meddling.
Lights over Lapland webcam operator Chad Blakely captured the first chemical puffs. Video below from Adrien Mauduit documents the spectacle.
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.
It began with a routine check of space weather before bed. I say routine because it used to be daily ritual until a few months ago when work took siege of every waking moment. Not so long ago I would have been all over a geomagnetic storm, auroras are my thing and I miss them. SpaceWeather http://spaceweather.com/ told of “the next geomagnetic storm”, Earth’s exit from one solar stream and anticipated arrival of another on November 18. Oh man, what solar stream? Then I remembered Adrien Mauduit, newly discovered astro-photographer and visionary whose efforts warm my heart.
Sure enough, Mauduit not only knew of last weekend’s solar storm, he captured its ethereal beauty in HD.
Adrien Mauduit wrote “If you missed the show last night, here’s a recap of what happened from the Aurora observatory on Senja island, Norway. “
September 2nd marks a historic 150th anniversary. On this day in 1859 miners in Virginia woke at 3 am thinking glowing skies signaled sunrise. From the North Pole to Cuba, Hawaii, most of Mexico, parts of Central America and Colombia, China and Japan, brilliant auroras delivered a electromagnetic circus. All across Europe and North America telegraph wires sparked, stations caught fire, some operators reported sending and receiving messages even after disconnecting power lines.
150 years ago British astronomer Richard Carrington witnessed a unprecedented solar flare – today we know it as the Carrington Event. A similar event today would devastate life as we know it. Ponder weeks, months, possibly years without electricity, internet, ATMs, GPS, power to pump water and fuel, air, road or rail travel. Space weather is real and it matters.
On September 3rd space weather predicts a solar sector boundary crossing.
Our sun produces wind (currently 316.9 Km/second) blasts across the cosmos. Just like Earth, the Sun has a magnetic field – known as the interplanetary magnetic field (IMF). Whipped into 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 – during that time expect occasional high frequency radio wave disruption, wonky GPS and cell phone service peppered with sudden power grid failure events. On the upside, we’re treated to kick ass auroras.
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.