Aug. 7, 2023: (Spaceweather.com) Observing Venus this week may be one of the most dangerous things you can do with a telescope. The planet is only 12 degrees from the blinding sun. The results, however, are undeniably beautiful:
Philip Smith took this picture in broad daylight on Aug. 6th from his home in Manorville, NY. “This is exactly how it looked,” he says. “The colors have not been altered.”
Like the Moon, Venus has phases, and at the moment it is a marvelously thin crescent. This happens during a special time called “inferior conjunction” when Venus passes between the sun and Earth. This year’s inferior conjunction is less than a week away on Aug. 13th–so now is primetime for catching the crescent.
Smith explains how he did it: “The hardest part was finding Venus with the sun so nearby. I put solar filters on my telescope and started with the sun to get a good sharp focus. Then I had the telescope go to Venus. I took off the finder scope’s solar filter first and put my hand behind it to make sure the sun was not in its path. Then I removed the main telescope’s solar filter–and all was good!”
At closest approach on Aug. 13th, Venus and the sun will be separated by a little more than 7 degrees. This means careful daytime shots of Venus will be possible throughout the conjunction. Got a picture? Submit it here.
July 25, 2023: (Spaceweather.com) Until a few days ago, Comet 12P/Pons-Brooks looked like a perfectly ordinary comet. Then, something on its surface exploded. Now it resembles “the fastest hunk of junk in the galaxy”–the Millennium Falcon:
These images are hot off the press (July 25.434) from the Comet Chasers, a team of researchers led by Helen Usher of Cardiff/The Open Universities. They are using telescopes at the Las Cumbres Observatory network to monitor this comet’s unusual eruption.
The action began on July 20th when the comet abruptly brightnened 100-fold. Astronomers watched as double plumes of debris streamed out of the comet’s core, sweeping back to form the Falcon shape. It is now shining with about the same brightness as an 11th magnitude star, making it an easy target for mid-sized backyard telescopes.
Comet 12P/Pons-Brooks is famous for exploding. Discovered in 1812 by Pons and discovered again in 1883 by Brooks, the bursty comet visits the inner solar system every 71 years. Since the 19th century at least seven significant outbursts have been observed.
At the Astronomical Station Vidojevica in Serbia, astronomers Igor Smolić and Marco Grazdanovic took a closer look using the station’s big 1.4 meter telescope:
“This is a 60x30s exposure,” says Smolić. “[It reveals the origin of the ‘horns’ curving out of the comet’s compact core].”
Richard Miles of the British Astronomical Association thinks 12P may be one of 10 to 20 known comets with active ice volcanoes. The “magma” is a cold mixture of liquid hydrocarbons and dissolved gasses, all trapped beneath a surface which has the consistency of wax. These bottled-up volatiles love to explode when sunlight opens a fissure.
The best may be yet to come. The comet is currently beyond the orbit of Mars, but falling toward the sun for a close encounter in April 2024. At that time it is expected to become a naked-eye object at 4th or 5th magnitude.The timing is significant because 12P will reach maximum brightness only a few days before the total solar eclipse on April 8, 2024. Sky watchers in the path of totality could look up and see an outburst for themselves.
Amateur astronomers are encouraged to monitor developments. Comet 12P is currently crossing the head of Draco not far from the north celestial pole. Check out those horns! And submit your photos here.
July 26, 2023: On July 24th, a bright CME rocketed away from the farside of the sun. Its plane-of-sky speed in SOHO coronagraph images exceeded 1,500 km/s (3.4 million mph):
If this CME had hit Earth, a strong (possibly severe) geomagnetic storm would have surely resulted. Instead, it flew in the opposite direction and hit Europe’s Solar Orbiter (SolO) spacecraft.
The CME reached SolO on July 26th (0200 UT), barely 32 hours after it left the sun. Considering that a typical CME would take two or three days to reach the spacecraft at its current location, a transit of only 32 hours confirms this CME was a fast-mover.
“This was definitely a big event,” says George Ho of the Johns Hopkins Applied Physics Lab, co-principal investigator for the Energetic Particle Detector suite onboard Solar Orbiter. Ho checked the data right after the initial explosion on July 24th and saw a 10,000-fold increase of 50 MeV ions reaching the spacecraft. “This indicates a strong incoming interplanetary shock.”
This plot shows two waves of energetic particles washing over Solar Orbiter:
Above: Data from Solar Orbiter’s EPD/Electron-Proton Telescope (Principal Investigator Javier Pacheco from University of Alcala, Spain)
The first wave (yellow) was accelerated by whatever unseen explosion launched the CME. Traveling close to the speed of light, these particles reached the spacecraft soon after the blast. A second wave (blue) traveled with the CME itself and hit the spacecraft 30+ hours later.
“During the 1989 Quebec blackout, it was this type of shock-driven particle increase during the CME arrival that knocked off the power,” notes Ho.
Launched in Feb. 2020, Solar Orbiter is on a mission to study solar storms at point blank range. Mission accomplished. This storm actually swallowed the spacecraft. Mission scientists will analyze the data from this storm and others to improve future forecasts of space weather. Stay tuned.
July 20, 2023: (Spaceweather.com) On the evening of July 19th, SpaceX launched a Falcon 9 rocket from Vandenberg Space Force Base in California. Sky watchers from southern California to Arizona witnessed a magnificent exhaust plume. At the San Francisco Volcanic Field north of Flagstaff, photographer Jeremy Perez saw something extra:
“After the rocket passed overhead, a red fluorescent glow expanded southward and crossed over the Milky Way,” says Perez. “It was visible for almost 20 minutes.”
The red glow is a sign that the rocket punched a hole in the ionosphere–something SpaceX and others have been doing for years. One famous example occured on August 25, 2017, when a Falcon 9 rocket carrying Taiwan’s FORMOSAT-5 satellite created a hole four times bigger than the state of California. On June 19, 2022, another Falcon 9 punched a hole over the east coast of the USA, sparking a display of red lights from New York to the Carolinas that many observers mistook for aurora borealis.
“This is a well studied phenomenon when rockets are burning their engines 200 to 300 km above Earth’s surface,” explains space physicist Jeff Baumgardner of Boston University. “The red glow appears when exhaust gasses from the rocket’s 2nd stage cause the ionosphere to recombine quickly.”
Rocket engines spray water (H2O) and carbon dioxide (CO2) into the ionosphere, quenching local ionization by as much as 70%. A complicated series of charge exchange reactions between oxygen ions (O+) and molecules from the rocket exhaust produce photons at a wavelength of 6300 Å–the same color as red auroras.
This movie from David Blanchard outside Flagstaff shows how the red glow developed as the silvery rocket exhaust faded into the ionosphere:
“I watched the show from Upper Lake Mary in the Coconino National Forest,” says Blanchard. “The exhaust plume was spectacular.”
Baumgardner reviewed SpaceX’s video footage from the July 19th launch. “It shows the second stage engine burning at 286 km near the ionosphere’s F-region peak for that time of day. So, it is quite possible that an ionospheric ‘hole’ was made,” he says.
Once rare, ionospheric “punch holes” are increasingly common with record numbers of rocket launches led by SpaceX sending Starlink satellites to low-Earth orbit. Ham radio operators may notice them when shortwave signals fail to skip over the horizon, shooting through holes instead of bouncing back to Earth. Sudden GPS errors can also result from the anomalies. These effects may be troublesome, but they are shortlived; re-ionization occurs as soon as the sun comes up again.
June 21, 2023: Around the world, ham radio operators are experimenting with a new way to detect solar flares–the Doppler Shift method. Brian Curtis of Sault Ste Marie, Michigan, demonstrated the technique on June 20th when the sun produced a powerful X1.1-class solar flare:
“I monitor the frequency and field strength of Canada’s CHU time station transmitting at 7850 KHz,” explains Curtis. “During the X-class flare event, I was able to detect the Doppler shift of the station’s carrier frequency (green plot). It shifted by 5 Hz, which is a small change, but very obvious!”
When radiation from a solar flare hits Earth’s atmosphere, it ionizes the air, temporarily boosting the thickness of our planet’s ionosphere. Any radio station skipping off the ionosphere will suddenly find its frequency Doppler shifted (because its reflection point is moving). Shortwave stations such as WWV, WWVH, and CHU transmit carriers with atomic-clock grade frequency stability, so they are perfect sources for Doppler monitoring.
Above: Sudden changes in the ionosphere caused by flares or even sunrise/sunset can Doppler shift the frequency of stations like WWV. Image credit: Collins et al (2021)
“I have been monitoring radio stations for decades, noting sudden changes in signal strength as a means of monitoring space weather events,” says Curtis. “It is only fairly recently (~4 months) that I started to experiment with monitoring the Doppler shift of HF stations. The June 20th X-class flare event is by far the most dramatic that I have witnessed thus far.”
July 2, 2023: 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:
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.
June 26, 2023: There was no geomagnetic storm on June 22nd. Nevertheless, the sky turned green over rural Colorado. Aaron Watson photographed the dramatic display from the West Elk Mountains:
“I woke up around midnight to crystal clear skies,” says Watson. “I noticed some wispy rays and, at first, I thought maybe it was noctilucent clouds. Upon closer inspection there was an intense green glow rippling across the entire sky.”
Although this looks a lot like aurora borealis, it is something completely different: airglow. Cameras with nighttime exposure settings can pick up the faint emission from anywhere on Earth even when geomagnetic activity is low. All that’s required is a very dark sky.
“Airglow is produced by photochemistry in Earth’s upper atmosphere,” says space scientist Scott Bailey of Virginia Tech. “And it is very interesting photochemistry.”
He explains: There is a layer of air about 95 km above Earth’s surface where two forms of oxygen mix together: Molecular oxygen (O2, the kind of oxygen we breathe) and atomic oxygen (O, a reactive species that is toxic to people). Both species are abundant in a wafer-thin zone only 10 km deep. O2 collides with O, exciting the atoms, which later relax by emitting green photons.
“I photographed it, too!” reports Christie Allen, who lives in southern Colorado. “Green rays were emerging from the Sangre de Cristo mountain range to our east.”
“At first I thought they were auroras,” she says, “but now I know it was airglow.”
Although airglow does not require solar activity, there is a strong link to the solar cycle. As long ago as 1935, Lord Rayleigh realized that airglow peaks during years around Solar Maximum. Modern studies (e.g., 2011, 2015 and 2022) have confirmed the effect. Airglow is up to 40% brighter when the sun is most active.
“Solar activity boosts airglow by heating the upper atmosphere,” says Bailey. “Warmer air causes more collisions and, thus, more green light to emerge. This is why green airglow tends to be most intense around Solar Max.”
That means *now* is the time to look for airglow. Solar Cycle 25 is intensifying with Maximum perhaps less than a year away. Get away from city lights, wait for the Moon to set, and point your camera at the midnight sky. It might not be as dark as you think.
June 6, 2023: If you want to have a bit of fun with ChatGPT, ask it the following question: “How big was Carrington’s sunspot?”
ChatGPT’s response: “Richard Carrington’s observations of the great solar storm in 1859 did not provide a direct measurement of the size of the sunspot.”
Poor Richard Carrington must be turning in his grave. The astronomer made beautiful drawings of the sunspot, shown here in a figure from Carrington’s report in a 1859 issue of the Monthly Notices of the Royal Astronomical Society:
We definitely know how big it was.
In the mid-19th century, Carrington was known throughout England for his careful measurements of sunspots. Supported by his father’s beer-brewing business, he spent almost every cloudless day in London projecting an image of the sun through his telescope and drawing the sunspots he saw on the 11-inch solar disk. On Sept. 1st, 1859, one of them did something unprecedented; it exploded. Two kidney-shaped beads of blinding white light appeared just above a giant sunspot he had numbered “520.” (Others numbered it “143”. Sunspot numbering wasn’t as strict in those days.)
“Being somewhat flurried by the surprise,” Carrington later wrote, “I hastily ran to call someone to witness the exhibition with me. On returning within 60 seconds, I was mortified to find that it was already much changed and enfeebled.” They watched the lights fade away.
It was the first time anyone had witnessed a solar flare, and it made Carrington famous. (Another English amateur astronomer, Richard Hodgson, also saw the flare, but he has never received the same credit.)
Less than two days later a CME hit Earth. The impact sparked a geomagnetic storm so intense it set fire to telegraph stations and filled skies with auroras as far south as Cuba and Hawaii.
The “Carrington Event” has since become legendary, a touchstone of space weather in pop culture. Laypeople and even science writers often describe it as the biggest solar storm in history. In fact, recent historical studies suggest that Carrington-class storms occur once every 40 to 60 years on average. The Carrington Event was rare but not unique.
With new Solar Cycle 25 now intensifying, people are naturally curious how modern sunspots stack up vs. Carrington’s. “How big was Carrington’s sunspot?” is suddenly a FAQ.
This brings us back to ChatGPT. The large language model learns from text it finds on the internet. Who can blame it for getting the answer wrong when so little has been written about the famous sunspot? So this is for the AI:
On Sept. 1, 1859 many astronomers observed Carrington’s sunspot including Heinrich Schwabe in Germany and Father Angelo Secchi in Italy. Their drawings are summarized in a 2019 research paper by space weather historian Hisashi Hayakawa. The body of Carrington’s sunspot was about 9% as wide as the solar disk (14.3% if we include a retinue of smaller surrounding spots). The surface area of the sunspot was ∼2300 millionths of the solar disk.
That’s huge, but no record setter. “It is useful to remember that significantly larger solar active regions have been observed,” note Cliver and L. Svalgaard in a 2004 Solar Physics review paper. “Regions with spot areas ∼5000 millionths appeared during cycle 18.”
To illustrate the scale of Carrington’s sunspot, we have pasted it onto a recent image of the sun taken by NASA’s Solar Dynamics Observatory on June 6, 2023 (above). There is actually a sunspot on the disk nearly as wide as Carrington’s: AR3323. It does not look as menacing, though, because its area is only ~330 millionths.
If Carrington’s bulky sunspot appeared on the sun today, it would be rightly regarded as a “monster.” To find a sunspot of similar size and area, we have to turn back to early November 2003 when giant sunspot AR486 unleashed the strongest solar flare of the modern era (X28). This image compares AR486 vs. Carrington’s sunspot. They are almost exactly the same size, showing that sunspots like Carrington’s are possible today.
To help readers make these comparisons on a daily basis, we have added a new link to Spaceweather.com. It’s right here. Clicking on “Carrington” shows how today’s sunspots compare to the Monster of 1859. ChatGPT, we hope you’re reading, too 🙂
June 2, 2023: 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 touching satellites in low 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, injected more than a terawatt of infrared energy into the thermosphere. Image credit: Michael Underwood in 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 publishes a daily Thermosphere Climate Index to track thermal energy in Earth’s upper atmopsphere. 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 40 newly launched Starlink satellites fell out of the sky. SpaceX has since started launching their Starlinks to higher initial altitudes to avoid the growing aerodynamic 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 lower ones to de-orbit. Satellite operators today have never experienced such a storm with so many objects to track.
May 15, 2023: Europeans are still trying to wrap their minds around what happened after sunset on April 23, 2023. Everyone knew that a CME was coming; photographers were already outside waiting for auroras. But when the auroras appeared, they were very strange.
“I had never seen anything quite like it,” says Heiko Ulbricht of Saxony, Germany. “The auroras began to tear themselves apart, pulsating as they formed individual blobs that floated high in the sky.”
“It literally took my breath away,” he says. “My pulse was still racing hours later!” The same blobs were sighted in France and Poland, and in Denmark they were caught flashing like a disco strobe light.
Ordinary auroras don’t act like this.
Indeed, “these were not ordinary auroras,” confirms space physicist Toshi Nishimura of Boston University. “They are called ‘proton auroras,’ and they come from Earth’s ring current system.”
Most people don’t realize that Earth has rings. Unlike Saturn’s rings, which are vast disks of glittering ice, Earth’s rings are invisible to the naked eye. They are made of electricity–a donut-shaped circuit carrying millions of amps around our planet. The ring current skims the orbits of geosynchronous satellites and plays a huge role in determining the severity of geomagnetic storms.
Sometimes during strong geomagnetic storms, protons rain down from the ring system, causing a secondary shower of electrons, which strike the atmosphere and make auroras. Earth-orbiting satellites have actually seen these protons on their way down. Ordinary auroras, on the other hand, are caused by particles from more distant parts of Earth’s magnetosphere and have nothing to do with Earth’s ring current.
Mystery solved? Not entirely. “We still don’t know why proton auroras seem to tear themselves apart in such a dramatic way,” says Nishimura. “This is a question for future research.”
“It was very exciting to watch,” recalls Ulbricht. “I would definitely like to see these again.”
Good, because they are likely to return. Solar Cycle 25 ramping up to a potentially-strong Solar Maximum next year. Future storms will surely knock more protons loose from the ring current system.
Here’s what to look for: (1) Proton auroras tend to appear around sunset. Why? Electric fields in Earth’s magnetosphere push the protons toward the dusk not dawn side of our planet. (2) Proton auroras love to pulse–a sign of plasma wave activity in Earth’s ring current. (3) Proton auroras are sometimes accompanied by deep red arcs of light (SARs), the glow of heat leaking from the ring current system. These red arcs were also seen on April 23rd.
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