Dark Plasma Eruption from a Reversed Polarity Sunspot

Aug. 14, 2022: The sun just hurled a plume of cool, dark plasma into space following an explosion around sunspot AR3076. NASA’s Solar Dynamics Observatory recorded the blast on August 14th:

Traveling faster than 600 km/s (1.3 million mph), the plume tore through the sun’s outer atmosphere, creating a coronal mass ejection (CME). Coronagraph images from the Solar and Heliospheric Observatory (SOHO) confirm that the CME has an Earth-directed component. It could sideswipe Earth’s magnetic field on Aug. 18th, producing minor to moderate geomagnetic storms.

REVERSED POLARITY SUNSPOT: The sunspot that produced the dark plasma explosion is a little unusual. It has its signs backwards.

Above: A magnetic map of the sun’s surface from NASA’s Solar Dynamics Observatory.

According to Hale’s Law, Solar Cycle 25 sunspots in the sun’s northern hemisphere should have a -/+ polarity; negative on the left, positive on the right. However, the magnetogram above shows the opposite. AR3076 is a reversed polarity sunspot.

Studies show that about 3% of all sunspots violate Hale’s Law. In many ways, reversed polarity sunspots are just like other sunspots. For instance, they have the same lifespan and tend to be about the same size as normal sunspots. In one key way they are different: According to a 1982 survey by Frances Tang of the Big Bear Solar Observatory, reversed polarity sunspots are more than twice as likely to develop complex magnetic fields mixing + and – together. Reversed polarity sunspots are therefore more likely to explode.

This one sure did, and a CME is now heading for Earth. Don’t miss the impact.

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A New Form of Space Weather on Betelgeuse

August 12, 2022: You’ve heard of a CME, a “coronal mass ejection.” They happen all the time. A piece of the sun’s tenuous outer atmosphere (corona) blows off and sometimes hits Earth. Something far more terrible has happened to Betegeuse. The red giant star produced an SME, or “surface mass ejection.”

Above: An artist’s concept of an SME on Betelgeuse. Credit: Elizabeth Wheatley (STScI)

Astronomers believe that in 2019 a colossal piece of Betelgeuse’s surface blew off the star. The mass of the SME was 400 billion times greater than a CME or several times the mass of Earth’s Moon. Data from multiple telescopes, especially Hubble, suggest that a convective plume more than a million miles across bubbled up from deep inside the star, producing shocks and pulsations that blasted a chunk off the surface.

“We’ve never before seen such a huge mass ejection from the surface of a star,” says Andrea Dupree of the Harvard-Smithsonian Center for Astrophysics, who is leading the study. “Something is going on that we don’t completely understand.”

After it left the star, the SME cooled, forming a dark cloud that famously dimmed Betelgeuse in 2019 and 2020. Even casual sky watchers could look up and see the change. Some astronomers worried that the dimming foreshadowed a supernova explosion. The realization that an SME is responsible has at least temporarily calmed those fears.

Above: A Hubble image of Betelgeuse located in the shoulder of Orion.

Betelgeuse’s brightness has since returned to normal, but something strange is still going on. Astronomers have long known that Betelgeuse is a variable star with a 430-day period. Its metronome-like change in brightness has been observed for more than 200 years. As Betelgeuse recovers, however, those pulsations are no longer regular: See the data. Spectra taken by Hubble and the Tillinghast telescope in Arizona imply that years later the surface of Betelgeuse is still bouncing like a plate of gelatin dessert–a testament to the ferocity of the blowout.

Betelgeuse is so large that if it replaced the sun at the center of our solar system, its atmosphere would extend past Jupiter. Dupree used Hubble to resolve hot spots on the star’s surface in 1996. This was the first direct image of a star other than the sun.

What’s happening now “is a totally new phenomenon that we can observe directly and resolve surface details with Hubble,” says Dupree. “We’re watching stellar evolution in real time.”

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Balloons Detect an Earthquake from the Stratosphere

August 10, 2022: If you want to detect an earthquake on Venus–good luck. The planet’s surface is hot enough to melt lead, and the atmospheric pressure is crushing. No ground-based seismometer could possibly survive.

What’s an extraterrestrial seismologist to do? Launch a balloon.

Above: Researchers prepare to launch a Strateole-2 balloon with sensors capable of detecting earthquakes from thousands of kilometers away.

A new paper just published in the Geophysical Research Letters reports the detection of a magnitude 7.3 earthquake by a fleet of balloons floating through the stratosphere above Indonesia’s Flores Sea. Onboard infrasound sensors registered acoustic waves rippling upward from the sea surface below, proving that, here on Earth, balloons can be used as seismometers.

“The same technique should work in the atmosphere of Venus,” says Raphael Garcia, the study’s lead author and a planetary scientist at the Institut Supérieur de l’Aéronatique et de l’Espace of the University of Toulouse. “Balloon-based sensors could float high above Venus’s deadly surface, collecting data at a safe distance.”

In the fall of 2021, the Centre National d’Etudes Spatiales (CNES) launched a fleet of 16 balloons from Mahé Island in the Seychelles archipelago. Unlike ordinary weather balloons, which explode in a matter of hours, these were “superpressure balloons,” which can remain aloft for months. Stratospheric winds carried them over the Flores Sea just in time for the temblor.

Above: Position of the quake in Flores Sea (blue square) with ground seismometers (purple stars) and the Strateole-2 balloons (red circles)

Four balloons picked up the undersea quake on Dec. 14, 2021. Combining their signals, researchers pinpointed the epicenter within 300 km, the magnitude of the quake within 0.8 units, and its onset within 50 seconds. Furthermore, waveforms recorded by the infrasound sensors were detailed enough to sense structures in the Earth 100 km deep.

Garcia would like to do the same thing on Venus. “We know nothing of its interior,” he says. “We don’t know how it’s made inside, and seismology is one of the best tools to figure that out.”

Seismic balloons could come in handy on our own planet, too. “Balloons could be used to cover ocean regions where conventional seismometers are not yet deployed,” notes Garcia.  “Another advantage: Balloons may be rapidly deployed just after a big quake for monitoring aftershocks.”

Above: Acoustic waves recorded by the four balloons during the Flores Sea earthquake.

The test flights have already unearthed a curiosity in South America. On Nov. 28, 2021, just one of the balloons detected a magnitude 7.5 earthquake in northern Peru. The infrasound frequency, 0.23 Hz, was higher than expected; for comparison, the Flores Sea quake registered a more typical 0.085–0.125 Hz. Garcia’s team believes the high pitch may have been caused by a “ringing” of sediments in the Amazonian basin.

Sensing earthquakes from the stratosphere is relatively new. Researchers at Caltech and the Jet Propulsion Laboratory did it for the first time in July 2019. Garcia’s study marks the first time an earthquake was detected by more than one balloon. It won’t be the last.

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Surprise Geomagnetic Storm

Aug. 8, 2022: A solar wind stream hit Earth’s magnetic field on August 7th. At first, the stream’s velocity was low, but during the day it sped up to more than 600 km/s, ultimately triggering a G2-class (moderately strong) geomagnetic storm. This event was not in the forecast, so the resulting auroras came as a surprise.

“I was already in bed getting ready for sleep when the storm began,” says Ruslan Merzlyakov. “Rushing to the beach in Nykøbing Mors, I was able to photograph the first summer auroras in Denmark in 5 years.”

“Seeing the lights dance on a warm summer night was a great experience!” he says.

In North American, auroras spilled across the Canadian border as far south as Pennsylvannia. In Wayne County, PA, Sujay Singh photographed both red auroras and STEVE. Auroras were also sighted in Montana and the Dakotas.

The solar wind stream that sparked this display is a bit of a puzzle. It might be the early arrival of a stream originally expected on Aug. 9th, flowing from an equatorial hole in the sun’s atmosphere. Or, perhaps, a CME was involved. A discontinuity in solar wind data at 0045 UT on Aug. 7th hints at a shock wave embedded in the solar wind. These days, the active sun is producing so many minor explosions, it is easy to overlook faint CMEs heading for Earth.

“Earth’s magnetic field is still reverberating on August 8th,” reports Stuart Green, who recorded the event using a backyard magnetometer in the UK:

Despite the surprise, subscribers to our Space Weather Alert Service were aware of the storm. Instant text alerts announced the arrival of the solar wind and the subsequent G2 event. Aurora alerts: SMS Text

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Blue Jet Lightning Sighted Over Texas

August 4, 2022: Seeing one blue jet is rare. Photographer Matthew Griffiths just caught several of them over the Big Bend National Park in Texas. “This is by far the best,” he says:

Above: A blue jet emerges from a thunderhead in Big Bend National Park, photographed by Matthew Griffiths in Marfa, Texas: more.

Griffiths is an amateur photographer, primarily interested in wildlife and the Milky Way. “On July 28th, I was starting a five night West Texas road trip to capture the Milky Way,” he says. “But with thunderstorms in the distance I decided to try for red sprites instead.”

He ended up photographing the sprite’s elusive cousin, the blue jet. First recorded by cameras on the space shuttle in 1989, blue jets are part of a growing menagerie of cloudtop “transient luminous events” such as sprites, ELVES and green ghosts. They are all elusive, but blue jets may be the hardest of all to catch.

“We’re not sure why ground-based observers see them so rarely,” says Oscar van der Velde of the Lightning Research Group at the Universitat Politècnica de Catalunya. “It might have something to do with their blue color. Earth’s atmosphere naturally scatters blue light, which makes them harder to see. Blue jets might be more common than we think.”

A rookie mistake might have helped Griffiths. “This is only my second time trying for sprites. I might have aimed my camera too close to the cloud tops where bright lightning washed out the sprites; in fact, I couldn’t find any sprites in my photos. But I think my camera angle was just right for catching the bright blue jet.”

Above: A zoomed-in view showing the jet’s sharp lance-like core and a diffuse fan of electric-blue overhead.

Blue jets might look like lightning, but they are not the same. Normal lightning carves a scorching-hot path through the atmosphere, heating the air to 30,000 degrees Celsius. Blue jets are made of cold plasma akin to gas inside a fluorescent light bulb. You could touch one with your hand and it might not hurt.

And, of course, they go up instead of down. Photos taken from the International Space Station (ISS) show that blue jets reach astonishing altitudes, as high as 170,000 feet. This is high enough to touch the ionosphere, possibly forming a new and poorly understood branch of Earth’s global electrical circuit.

“Also,” says van der Velde, “there can be considerable production of NOx and ozone by these discharges, potentially affecting the chemistry of the upper atmosphere.”

Clearly, it is important to study blue jets. Photographers, now you know where to look.

Space Traffic Boosts Noctilucent Clouds

July 29, 2022: Never before have so many rockets been launched. In 2021, the space agencies of Earth broke the all-time record for global rocket launches with 133, and in 2022 it looks like the record will be broken again with more than 150. China and SpaceX are big contributors to this increase.

High above Earth, something else is increasing: Noctilucent clouds (NLCs). It’s no coincidence. A new paper just published in the AGU journal for Earth and Space Science confirms that “space traffic has a strong influence on the interannual variability of these bright mesospheric clouds.”

Above: Noctilucent clouds over Anchorage AK on July 26, 2022. Credit: Todd Salat.

Noctilucent clouds are a natural phenomenon. During summer months, wisps of water vapor rise up to the mesosphere, 83 km high, and crystalize around specks of disintegrated meteoroids. Sky watchers at northern latitudes can easily see the clouds, which are filled with fine ripples and shine at night with an electric blue color.

Rocket launches are boosting NLCs. A team of researchers led by Michael Stevens of the Naval Research Lab in Washington, DC, looked at data from NASA’s AIM spacecraft, which was launched in 2007 to study noctilucent clouds. They found a strong correlation between the number of rockets launched each July and the abundance of clouds in the mesosphere. 

Above: July rocket launches (black) vs. the abundance of noctilucent clouds (red)

The link is simple: Rockets produce plumes of water vapor. Winds carry these plumes toward the polar mesosphere where they become raw material for NLCs. Rockets launched in the “morning” between 11 pm and 10 am local time are most effective. During those times, diurnal wind patterns push the plumes toward the noctilucent zone.

Researchers have long known that rockets can produce NLCs. Seminal studies led by Stevens in the early 2000s linked specific space shuttle launches to outbursts of the clouds over both of Earth’s poles (refs: #1, #2). The shuttle program ended in 2011, but the “rocket effect” has continued and probably increased (researchers are still investigating the trends at mid-latitudes during the satellite era).

This is good news for sky watchers who love seeing “frosted meteor smoke” light up the night. Rockets make NLCs both brighter and more widespread. Researchers, on the other hand, may have mixed feelings. NLCs can be a sensitive indicator of changes to Earth’s climate system–e.g., revealing long-range teleconnections and the abundance of  greenhouse gases in the upper atmosphere. Rocket launches could swamp these delicate signals.

Either way, the launch schedule continues. Be alert for noctilucent clouds!

Cosmic Rays are Decreasing

July 26, 2022: Cosmic rays in the atmosphere are rapidly subsiding. In the past year alone, radiation levels in the air high above California have plummeted more than 15%, according to regular launches of cosmic ray balloons by Spaceweather.com and Earth to Sky Calculus. The latest measurement on July 23, 2022, registered a 6 year low:

This development, while sudden, is not unexpected. Cosmic rays from deep space are repelled by solar activity; when one goes up, the other goes down. Since 2021, Solar Cycle 25 has roared to life faster than forecasters expected. The onset of the new solar cycle has naturally led to a decrease in cosmic radiation reaching Earth.

To many readers this may sound counterintuitive. After all, don’t solar flares produce radiation? Yes, but most high-energy radiation doesn’t come from the sun; it comes from deep space. Every day galactic cosmic rays from distant supernova explosions pass through the Solar System. When they hit the top of Earth’s atmosphere, they create a secondary spray of radiation, which we measure using sensors onboard our balloons.

The sun makes it more difficult for these cosmic rays to reach Earth. Simply put, when the sun is active, its magnetic field gets stronger and more tangled. Cosmic rays have trouble penetrating the magnetic thicket. Also, individual CMEs sweep aside cosmic rays, causing sharp reductions called “Forbush Decreases.” The two effects blend together to bring daily radiation levels down.

Above: Earth to Sky students launch a cosmic ray balloon on July 23, 2022.

There is considerable interest in atmospheric cosmic rays. Climate scientists are engaged in a lively debate about whether or not cosmic rays affect cloud cover. (The consensus seems to be mostly not.) Cosmic rays also penetrate aircraft, boosting the risk of cancer among frequent fliers and flight crews.

Solar Maximum is expected in 2025, so the downward trend in cosmic radiation should continue for years to come. How low will it go? Stay tuned for updates.

Solar Tsunami and CME

July 21, 2022: Sunspot AR3060 exploded during the early hours of July 21st (0110 UT), producing a C5-class solar flare and a solar tsunami. The “tsunami” is the shadowy shock wave seen racing away from the blast site in this extreme ultraviolet movie from NASA’s Solar Dynamics Observatory:

Soon after the explosion, the US Air Force reported a Type II solar radio burst–a natural form of radio noise produced by shock waves in the leading edge of a CME. Characteristics of the burst suggested that a CME was tearing through the sun’s atmosphere at a speed of 1063 km/s (2.4 million mph).

Coronagraphs onboard the Solar and Heliospheric Observatory (SOHO) have since seen the CME:

In the movie we see a superposition of multiple CMEs. The brightest clouds at the 8 o’clock and 10 o’clock positions may be from farside eruptions. They are not heading for Earth. Of greater interest is a faint full-halo CME which emerges just before 0206 UT. That one was launched by the tsunami and is squarely inside the Earth strike zone. NOAA forecasters expect it to arrive on July 23rd, possibly sparking G2-class geomagnetic storms. Solar flare alerts: SMS Text.

The Bastille Day Event

July 14, 2022: You know a solar flare is strong when even the Voyager spacecraft feel it. Twenty-two years ago today (July 14, 2000) the sun exploded with so much force, it sent shockwaves to the edge of the solar system.

Earth was on the doorstep of the blast, nicknamed the “Bastille Day Event” because it happened on the national day of France. Subatomic particles accelerated by the flare peppered satellites and penetrated deep into Earth’s atmosphere. Radiation sensors on Earth’s surface registered a rare GLE–a “ground-level event.”

Above: SOHO images of the Bastille Day solar flare (left) and CME (right). The onset of snow in the images is a result of energetic protons hitting the spacecraft

“People flying in commercial jets at high latitudes would have received double their usual radiation dose,” says Clive Dyer of the University of Surrey Space Centre in Guildford UK, who studies extreme space weather. “It was quite an energetic event–one of the strongest of the past 20 years.”

A day later the CME arrived. Impact on July 15th sparked an extreme (Kp=9) geomagnetic storm. The sun had just set on the east coast of North America when the first auroras appeared.

“I was out in the yard doing chores and saw bright red auroras straight overhead,” recalls Uwe Heine of Caswell County, North Carolina. “I called over to our neighbor, Carrie, who was also outside. I told her those were not sunset colors. It was an aurora, and super rare to see this far south!”

Above: Auroras on July 15, 2000, photographed by (left) Grant Privett of Farnborough UK and (right) NASA’s IMAGE spacecraft.

In New York, the sky exploded with light, recalls Lou Michael Moure. “I was living on Long Island at the time. A family member came running into my room, begging me to come outside to see ‘the sky on fire.’ The sky truly looked as if it was ablaze. Hues of white and green eventually gave way to reds that blanketed the heavens from horizon to horizon.”

By the time the storm was over on July 16th, auroras had been sighted as far south as Texas, Florida and Mexico.

A few other storms of the Space Age have have been equally strong, but the Bastille Day Event is special to researchers. It was the first major solar storm after the launch of SOHO, the Solar and Heliospheric Observatory. Data from the revolutionary young satellite taught researchers a lot, very quickly, about the physics of extreme flares.

Above: A modern MHD computer simulation of the Bastille Day explosion. Credit: Tibor Török et al., The Astrophysical Journal, 856:75 (22pp), 2018 March 20.

Tibor Török of Predictive Science, Inc., is one of many researchers still studying the Bastille Event decades later. “The event took place close to disk center, so we had a great view of the action,” he says. Török recently applied a modern magnetohydrodynamic (MHD) computer model to some of the data, and found that 1033 ergs of magnetic energy were released in the explosion–about the same as a thousand billion WWII atomic bombs.

No wonder the Voyagers felt it.

It took the Bastille Day CME months to reach the distant spacecraft. Voyager 2 felt it 180 days later, Voyager 1 took 245 days. Being near the edge of the solar system, both spacecraft were naturally bathed in high levels of cosmic rays. The CME swept aside that ambient radiation, creating a temporary reduction called a “Forbush Decrease.” Conditions returned to normal 3 to 4 months later and, finally, the storm was over.

Could another Bastille Day Event be in the offing? Solar Cycle 25 is ramping up, with a new Solar Max expected in 2025. Stay tuned.

more aurora photos: from Ronnie Sherrill of Troutman, North Carolina

Starfish Prime: The First Accidental Geomagnetic Storm

July 9, 2022: Sixty years ago today, one of the biggest geomagnetic storms of the Space Age struck Earth. It didn’t come from the sun.

“We made it ourselves,” recalls Clive Dyer of the University of Surrey Space Centre in Guildford UK. “It was the first anthropogenic space weather event.”

On July 9, 1962, the US military detonated a thermonuclear warhead 250 miles above the Pacific Ocean–a test called “Starfish Prime.” What happened next surprised everyone. Witnesses from Hawaii to New Zealand reported auroras overhead, magnificent midnight “rainbow stripes” that tropical sky watchers had never seen before. Radios fell silent, then suddenly became noisy as streetlights went dark in Honolulu.

Above: ‘Nuclear auroras’ viewed from Honolulu (left) and from a surveillance aircraft (right) on July 9, 1962.

Essentially, Starfish Prime created an artificial solar storm complete with auroras, geomagnetic activity, and blackouts. Much of the chaos that night was caused by the electromagnetic pulse (EMP)–a ferocious burst of radiation that ionized the upper atmosphere. Ionized air over the Pacific pinned down Earth’s magnetic field, then let it go again when the ionization subsided. The rebound created a manmade geomagnetic storm for hundreds of miles around the blast zone.

Dyer, who is widely known for his studies of extreme space weather events, was still in school when the bomb exploded. “In 1962 the Cold War was red hot, and we all thought the end was nigh,” he says. “Starfish Prime was a defining event.”

“The explosion led to the early demise of all the spacecraft in orbit at the time. These included Ariel-1, the UK’s first spacecraft, and Telstar-1, a US communications satellite which had the bad luck to be launched the very next day.”

Credit: R.E. Fischell, “ANNA-1B Solar Cell Damage Experiment,” Transcript of the Photovoltaic Specialists Conference, April 10, 1963, Washington DC.

Normally, geomagnetic storms bring down satellites via orbital decay. The upper atmosphere heats up and expands to the point where it can pull satellites down toward Earth. Starfish Prime was different.

“The explosion filled Earth’s magnetosphere with energetic electrons,” explains Dyer. “Electrons were injected by the gradual beta decay of fission products and added to our planet’s natural radiation belts. There were increased fluxes of trapped electrons for many years after the blast.”

These artificial electrons hit satellites hard, degrading their electronics and solar arrays.

“Ariel-1 became almost unusable after 4 days due to power degradation and tape recorder failure,” recalls Dyer. “The Telstar satellite lasted until November 1962 when its command decoder failed. It still managed to provide the first transatlantic TV feed, synchronize UK/US time to 1 microsecond and inspired the Tornado’s rock classic ‘Telstar,’ which used recordings of a flushing toilet played backwards.”

Starfish Prime serves as a warning of what could happen if Earth is blasted by high doses of radiation. Sixty years later, researchers are still learning what it can teach us about the vulnerability of power grids. An even scarier atmospheric explosion may have been Soviet test 184 (also designated K3) on October 22, 1962, which set fires and knocked out hundreds of miles of power lines in Kazakhstan. That, however, is a different anniversary.