We don't yet know if this flare hurled a CME into space. If it did, it could have a grazing Earth-directed component. Confirmation awaits fresh data from SOHO coronagraphs.
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Giant sunspot AR3664 unleashed another X-flare today (May 11th @ 0139 UT)--its strongest yet. NASA's Solar Dynamics Observatory captured a bright ultravolet flash from the category X5.8 explosion: Radiation from the flare caused a deep shortwave radio blackout over the Pacific Ocean. Ham radio operators and mariners may have noticed loss of signal at frequencies below 30 MHz for as much as an hour after the flare's peak.
We don't yet know if this flare hurled a CME into space. If it did, it could have a grazing Earth-directed component. Confirmation awaits fresh data from SOHO coronagraphs. https://spaceweather.com/
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The first of six CMEs hurled toward Earth by giant sunspot AR3664 hit our planet's magnetic field today. The impact on May 10th at 1645 UT jolted magnetometers around the world and sparked a severe (G4-class) geomagnetic storm. This storm is underway now. More CMEs are following close behind and their arrival could extend the storm into the weekend. Sign up for Space Weather Alerts to receive instant text messages when the CMEs arrive. The ongoing storm is producing low-latitude auroras in the southern hemisphere. Ken James sends this picture from the Snake Valley Observatory in Victoria, Australia: "The red, yellow and green colours were easily visible to my naked eye," says James. Readers in the USA should note that the southern latitude of Victoria, Australia, 37 degrees, is the same as the northern latitude of central California. That's how far down auroras could be seen if it were dark instead of daylight in North America. Why is this storm so severe? Take a look at the solar wind data from NOAA's DSCOVR spacecraft: After the CME struck, the speed of the solar wind blowing around our planet abruptly increased to more than 700 km/s. More importantly, south-pointing magnetic fields from the sun washed over the Earth, opening a crack in our planet's magnetosphere. Solar wind poured through the gap to turbo-charge the storm.
https://spaceweather.com/ Great sunspot AR3664 has hurled an astonishing five CMEs toward Earth. They're all in this frenetic 2-day coronagraph movie from the Solar and Heliospheric Observatory (SOHO): The two bright objects are Jupiter (left) and Venus (right). The CMEs will miss those planets and hit Earth instead.
According to a NOAA forecast model, the first three CMEs could merge for form a "Cannibal CME." Cannibal CMEs form when fast-moving CMEs overtake and gobble up slower CMEs in front of them. Internal shock waves created by such CME collisions do an good job sparking geomagnetic storms when they strike Earth's magnetic field. The Cannibal CME is expected to arrive on May 11th. It alone could spark a strong (G3) geomagnetic storm. With two more CMEs following close behind, storm levels could become extreme (G4), sparking auroras at mid- to low-latitudes across Europe and the USA. https://spaceweather.com/ Last week, Andreas Kohlmann of Samnaun, Switzerland, looked up and saw a 22° sun halo caused by ice crystals floating over the snowy landscape. His iPhone11 photo of the phenomenon captured something sky watchers often overlook--the 'hole in the sky' effect: The sky inside the halo is darker than the sky outside, creating a large but subtle disk of partial darkness around the sun. It exists because the ice crystals scatter light at least 22° away from the sun. "No light is refracted through smaller angles, so the area inside the halo is dark," explains retired atmospheric optics expert Les Cowley.
"Most rays are deflected through angles near to 22° to form the bright inner edge of the halo," he continues. "Red light is refracted less strongly than other colors, so the halo's inner edge is red hued." The 22° sun halo is the most common of all sun halos. The next time you see one, put on sunglasses to reduce the glare. You may see your own 'hole in the sky.' https://spaceweather.com/ A 100-mile wide shaft of cool air is about to race through Earth's atmosphere faster than 1500 mph. It's the shadow of the Moon created by Monday's total eclipse of the sun. This animation shows the progress of darkness across the United States: Solar eclipses make their own weather--starting with the temperature. How much the temperature falls depends on the humidity. Dry environments could see a drop of 8 to 14 degrees, less so if it’s humid. According to NASA, an eclipse in Zambia on June 21, 2001, reduced the temperature nearly 15 degrees.
The reduction in temperature can make clouds disappear. Satellites observing eclipses from Earth orbit have detected many examples. A 10-year study just published in Nature found that cumulus clouds begin dissipating when a mere 15 percent of the sun is covered. In some cases, clouds didn’t start to return until 50 minutes after maximum eclipse. This could be good news for eclipse chasers in Mexico and Texas, where widespread cloudcover is expected on April 8th. The eclipse itself might help clear the sky. Stay tuned! https://spaceweather.com/ Big sunspot AR3590 is as dangerous as it looks. Late yesterday (Feb. 21 @ 2307 UT), the active region produced a powerful X1.8-class solar flare with a shortwave radio blackout over the western USA and Pacific Ocean. NASA's Solar Dynamics Observatory recorded the extreme ultraviolet flash: Hours later (Feb. 22 @ 0635), the sunspot erupted again, producing an almost identical X1.7-class flare. Neither explosion produced a bright CME. This means the double flares will *not* cause a geomagnetic storm on Earth.
More explosions are in the offing. AR3590 has an unstable 'beta-gamma-delta' magnetic field that harbors energy for additional X-class explosions. https://spaceweather.com For the second time in less than a week, energetic solar protons are raining down on Earth's upper atmosphere. Forecasters call this a "solar radiation storm." Today's storm (near category S2) is rich in "hard protons" wiith energies greater than 50 MeV. It is causing a shortwave radio blackout inside the Arctic Circle and speckling the cameras of some Earth-orbiting satellites. The plot above shows storm data recorded by NOAA's GOES-18 satellite in Earth orbit. Sensors on the satellite are counting energetic protons as they pass by en route to Earth. Triggered by an explosion near the sun's southwestern limb (inset), this storm could last for another 24 hours.
https://spaceweather.com/ Yesterday (9 February) at 13.14 UT, the sun produced one of the most powerful solar flares in years, an X3.4-class explosion from just behind the sun's southwestern limb. NASA's Solar Dynamics Observatory (SDO) recorded the extreme ultraviolet flash: The source of the flare appears to be departing sunspot AR3575. Because the blast site was eclipsed by the edge of the sun, the flare was probably even stronger than its X3.4 classification suggests. This was a big explosion. Hours after the flare's peak, Earth was still feeling the effects of the blast. Solar protons energized by the flare are following curved magnetic field lines from the sunspot back to our planet. The resulting hailstorm, called a "radiation storm," is still intensifying at the time of this writing (9 February) and has just reached category S2: This plot shows what NOAA's GOES-18 satellite is seeing right now. The colored lines count the number of energetic protons streaming past the satellite en route to Earth. Green and blue are of special interest because they trace "hard protons" capable of upsetting spacecraft electronics, e.g., causing reboots of onboard computers and temporarily fogging cameras. The explosion also hurled a bright CME into space. It will not hit Earth. Instead, a NASA model of the CME shows it is heading for Mercury, Venus and Mars. It will hit all three planets this weekend. 10 February 2024: For the second day in a row, energetic protons from the sun are raining down on Earth. This is called a "solar radiation storm," and it is currently a category S2 event. A data-plot from NOAA's GOES-18 satellite shows how protons surged around our planet just after yesterday's X-class solar flare: The colored lines count the number of energetic protons streaming past GOES-18 en route to Earth. Green and blue are of special interest because they trace "hard protons" capable of upsetting spacecraft electronics, e.g., causing reboots of onboard computers. These particles can even reach all the way down to aviation altitudes, boosting dose rates for passengers and crews flying commercial planes over Earth's polar regions. We can actually *see* some of these protons. Take a look at this SOHO coronagraph movie of the sun hours after the flare: The "snow" in this movie is caused by the radiation storm. Each speckle is a solar proton striking the spacecraft's digital camera. This is a good example of how radiation storms can temporarily interfere with orbital imaging systems.
Another effect of the radiation storm is an ongoing blackout of shortwave radio transmissions around Earth's poles. This is called a "polar cap absorption event". Earth's magnetic field is guiding many of the incoming protons towards the poles, where they ionize the upper atmosphere; this, in turn, wipes out radio signals below 30 MHz. Many shortwave radios inside the Arctic Circle simply won't work until the radiation storm is over. https://spaceweather.com NOAA models confirm that a Cannibal CME will strike our planet on Dec. 1st. Cannibal CMEs form when a fast CME sweeps up a slower CME ahead of it. The combination contains intense, tangled magnetic fields that can do a good job sparking auroras when they reach Earth. If a Cannibal CME strikes Earth on Dec. 1st, as predicted, geomagnetic storm levels could reach category G3 (Strong). If so, here's what we can expect. The last G3-class storm on Nov. 5th sparked not only bright auroras, but also deep-red SAR arcs around the world. Greg Redfern photographed this example from the Shenandoah National Park in Virginia: "I didn't realize I had photographed an SAR arc until I processed my images the next day, stitching two of them together to reveal its shape," says Redfern. SAR arcs look like auroras, but they are not. They are the glow of heat energy leaking into the upper atmosphere from Earth's ring current system–a donut-shaped circuit carrying millions of amps around our planet. During the Nov. 5th geomagnetic storm, these red arcs were observed as far south as Texas and California. Auroras were observed as well -- "and they were INSANE," says Janne Maj Nagelsen, who watched the display from Stamnes, Vaksdal, Norway: "I have never seen such strong auroras," says Nagelsen. "Not to mention the colors. I mean look at the picture! They were totally, literally insane."
Auroras are caused by charged particles raining from space down upon Earth's atmosphere. Unlike SAR arcs, which are pure red, auroras can have a rich and stunning variety of colors. Both phenomena may be photographed on Dec. 1, 2023, when a Cannibal CME is expected to hit Earth. https://spaceweather.com/ Mercury and Mars are converging for a conjunction in the constellation Libra. The action is happening too close to the sun to see with the human eye, but coronagraphs on the Solar and Heliospheric Observatory (SOHO) are getting a great view of the action: At closest approach on Oct. 29th, the two planets will be only 20 arcminutes apart--a remarkable pair. If this were happening in a dark night sky, it would be headline news.
In a few months, it will be headline news. Mars and Mercury will loop around the sun for another even closer conjunction on January 27, 2024. During the event, the planets will be only 12 arcminutes apart--almost as close as Jupiter and Saturn were during the Great Conjunction of 2020. Both planets will be visible to the naked eye in the morning sky just before sunrise. Stay tuned. www.spaceweather.com
Sky watchers across the Americas witnessed a rare annular solar eclipse on Oct. 14th. The moon glided dead center across the solar disk, turning our star into a beautiful "ring of fire". Photos are pouring in from the eclipse zone. Check out our realtime gallery for the latest. In Nevada's Valley of the Moon (yes, that's a real place), Dr. Tony Phillips video-recorded the ring of fire through a bank of filter-perfect clouds:
Ring of Fire from Earth to Sky Calculus on Vimeo.
At the same time, two Earth to Sky Calculus helium balloons were en route to the stratophere on a mission to photograph the Moon's shadow from above. We might not know the results for a few days while the payloads are being recovered from remote wilderness areas. Stay tuned!
https://spaceweather.com/ Recent measurements by NASA's Solar Dynamic Observatory reveal a rapid weakening of magnetic fields in the polar regions of the sun. North and south magnetic poles are on the verge of disappearing. This will lead to a complete reversal of the sun's global magnetic field perhaps before the end of the year. An artist's concept of the sun's dipolar magnetic field. Credit: NSF/AURA/NSO. If this was happening on Earth there would be widespread alarm. Past reversals of our planet's magnetic field have been linked to calamities ranging from sudden climate change to the extinction of the Neanderthals. On the sun, it's not so bad. "In fact, it's routine", says Todd Hoeksema, a solar physicist at Stanford University. "This happens every 11 years (more or less) when we're on the verge of Solar Maximum." Vanishing poles and magnetic reversals have been observed around Solar Max in every single solar cycle since astronomers learned to measure magnetic fields on the sun. Hoeksema is the director of Stanford's Wilcox Solar Observatory (WSO), that is observing its fifth reversal since 1980. The last five polar field reversals observed at the Wilcox Solar Observatory (inset) "One thing we have learned from these decades of data is that no two polar field reversals are alike," he says. Sometimes the transition is swift, taking only a few months for the poles to vanish and reappear on opposite ends of the sun. Sometimes it takes years, leaving the sun without magnetic poles for an extended period of time. "Even more strange," says Hoeksema, "sometimes one pole switches before the other, leaving both poles with the same polarity for a while." Indeed, such a scenario could be playing out now. The sun's south magnetic pole has almost completely vanished, but the north magnetic pole is still hanging on, albeit barely. How does all this affect us on Earth? One way we feel solar field reversals is via the heliospheric current sheet: An artist's concept of the heliospheric current sheet. The sun is surrounded by a wavy ring of electricity that the solar wind pulls and stretches all the way out to the edge of the Solar System. This structure is a part of the sun's magnetosphere. During field reversals, the current sheet becomes extra wavy and highly tilted. As the sun spins, we dip in and out of the steepening undulations. Passages from one side to another can cause geomagnetic storms and auroras.
Most of all, the vanishing of the poles means we're on the verge of Solar Maximum. Solar Cycle 25 is shaping up to be stronger than forecasters expected, and its peak could be relatively intense. Stay tuned for updates! https://spaceweather.com/ When Vincent van Gogh painted "The Starry Night" in 1889, little did he know he was working at the forefront of 21st century astrophysics. A paper recently published in Nature Communications reveals that the same kind of waves pictured in the famous painting can cause geomagnetic storms on Earth. Above: Vincent van Gogh's 'Starry Night', which he painted in 1889 Physicists call them "Kelvin Helmholtz waves". They ripple into existence when streams of gas flow past each other at different velocities. Van Gogh saw them in high clouds outside the window of his asylum in Saint-Rémy, France. They also form in space where the solar wind flows around Earth's magnetic field. "We have found Kelvin-Helmholtz waves rippling down the flanks of Earth's magnetosphere", says Shiva Kavosi of Embry–Riddle Aeronautical University, lead author of the Nature paper. "NASA spacecraft are surfing the waves, and directly measuring their properties". This was first suspected in the 1950s by theoreticians who made mathematical models of solar wind hitting Earth's magnetic field. However, until recently it was just an idea; there was no proof the waves existed. When Kavosi's team looked at data collected by NASA's THEMIS and MMS spacecraft since 2007, they saw clear evidence of Kelvin Helmholtz instabilities. "The waves are huge" says Kavosi. "They are 2 to 6 Earth radii in wavelength and as much as 4 Earth radii in amplitude." This computer model shows van Gogh waves moving down the flank of Earth's magnetosphere. Credit: Shiva Kasovi. [full-sized animation] Imagine a wave taller than Earth curling over and breaking. That's exactly what happens. Kelvin-Helmholtz waves naturally break onto Earth's magnetic field, propelling energetic particles deep into the magnetosphere. This revs up Earth's radiation belts, triggering geomagnetic storms and auroras.
A key finding of Kavosi's paper is that the waves prefer equinoxes. They appear 3 times more frequently around the start of spring and fall than summer and winter. Researchers have long known that geomagnetic activity is highest around equinoxes. Kelvin-Helmholtz wave activity could be one reason why. Our planet's seasonal dependence of geomagnetic activity has always been a bit of a puzzle. After all, the sun doesn't know when it's autumn on Earth. One idea holds that, around the time of the equinoxes, Earth's magnetic field links to the sun's because of the tilt of Earth's magnetic poles. This is called the Russell-McPherron effect after the researchers who first described it in 1973. Kavosi's research shows that Kelvin-Helmholtz waves might be important, too. Northern autumn has just begun, which means Kelvin Helmholtz waves are rippling around our planet, stirring up "Starry Night" auroras. Happy autumn! www.spaceweather.com The sun is partying like it's 2002. That's the last time sunspot counts were as high as they are now. The monthly average sunspot number for June 2023 was 163, according to the Royal Observatory of Belgium's Solar Influences Data Analysis Center. This eclipses every month since Sept. 2002: Above: This plot is based on NOAA's interactive Solar Cycle Progression. Check it out! Solar Cycle 25 wasn't expected to be this strong. When it began in Dec. 2019, forecasters believed it would be a weak cycle akin to its immediate predecessor Solar Cycle 24. If that forecast had panned out, Solar Cycle 25 would be one of the weakest solar cycles in a century.
Instead, Solar Cycle 25 has shot past Solar Cycle 24 and may be on pace to rival some of the stronger cycles of the 20th century. The last time sunspot numbers were this high, the sun was on the verge of launching the Great Halloween Storms of 2003, which included the strongest X-ray solar flare ever recorded (X45), auroras as far south as Texas, and a CME so powerful it was ultimately detected by the Voyager spacecraft at the edge of the solar system. www.spaceweather.com If you're a satellite, this story is important. A series of geomagnetic storms in 2023 has pumped terawatts of energy into Earth's upper atmosphere, helping to push its temperature and height to a 20-year high. Air surrounding our planet is now touching satellites in Earth orbit and dragging them down. "Blame the sun," says Martin Mlynczak of NASA Langley. "Increasing solar activity is heating the top of the atmosphere. The extra heat has no effect on weather or climate at Earth's surface, but it's a big deal for satellites in low Earth orbit." Above: A severe geomagnetic storm on March 24, 2023, photographed by Michael Underwood from Yellowstone National Park Mlynczak is an expert on the temperature up there. For 20 years he has been using the SABER instrument on NASA's TIMED satellite to monitor infrared emissions from "the thermosphere," the uppermost layer of the atmosphere."Right now we’re seeing some of the highest readings in the mission's 21.5 year history," he says. The thermosphere is exquisitely sensitive to solar activity, readily absorbing energy from solar flares and geomagnetic storms. These storms have been coming hard and fast with the recent rise of Solar Cycle 25. "There have been five significant geomagnetic storms in calendar year 2023 that resulted in marked increases in the amount of infrared radiation (heat) in Earth's thermosphere," says Mlynczak. "They peaked on Jan. 15th (0.59 TW), Feb. 16th (0.62 TW), Feb. 27th (0.78 TW), Mar. 24th (1.04 TW), and April 24th (1.02 TW)." The parenthetical values are TeraWatts (1,000,000,000,000 Watts) of infrared power observed by SABER during each storm. The sensor obtains these numbers by measuring infrared radiation emitted from nitric oxide and carbon dioxide molecules in the thermosphere. Above: NASA's daily Thermosphere Climate Index tracks thermal energy in Earth's upper atmosphere. So far, Solar Cycle 25 is far ahead of Solar Cycle 24. Credit: Linda Hunt "The two storms exceeding 1 TW are the seventh and eighth strongest storms observed by SABER over the past 21.5 years," he says. "It is interesting to note that each successive storm in 2023 is generally stronger than its predecessors."Actually, it doesn't take a strong storm to cause problems. In Feb. 2022, a minor geomagnetic storm dumped enough heat into the thermosphere that 38 newly launched Starlink satellites fell out of the sky. SpaceX has since started launching their Starlinks to higher initial altitudes to avoid the drag.
If current trends continue, the thermosphere will warm even more in 2023 and 2024. This is a matter of concern because Earth's population of active satellites has tripled since SpaceX started launching Starlinks in 2019. The growing constellation of 4100 Starlinks now provides internet service to more than a million customers. An extreme geomagnetic storm like the Halloween Storms of 2003 could shift the positions of these satellites by many 10s of kilometers, increasing the risk of collisions and causing some of the lowest ones to de-orbit. Stay tuned as the warming continues. https://spaceweather.com |
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