Nov. 4, 2024: At the end of October, amateur astronomer Senol Sanli made a composite 31-day image of the month’s sunspots. Take a look. Notice anything?
The two hemispheres of the sun are not the same. There’s a lopsided distribution of sunspots, with three times more in the south compared to the north. According to hemispheric sunspot data from the Royal Observatory of Belgium (WDC-SILSO), October was the fifth month in a row the sun’s southern hemisphere significantly outperformed the north. You can see the same pattern visually in composite images from September, August, July, and, to a lesser extent, June 2024.
What’s going on? Solar physicists have long known that the two hemispheres of the sun don’t always operate in sync. Solar Max in the north can be offset from Solar Max in the south by as much as two years, a delay known as the “Gnevyshev gap.” The assymetry is illustrated in this graph of north-vs-south sunspot numbers from the last 6 solar cycles:
Is the sun’s southern hemisphere experiencing its Solar Max right now? Maybe. We won’t know for sure until years from now when we can look back and see the final shape of Solar Cycle 25. Meanwhile, stay tuned for more southern sunspots.
Sept. 20, 2024: (Spaceweather.com) Comet Tsuchinshan-ATLAS (C/2023 A3) has just emerged from behind the sun, and its appearance has astronomers buzzing with anticipation. “The comet is brightening rapidly,” says Australian astrophotographer Michael Mattiazzo, who has been monitoring the comet in dawn twilight:
Above: Comet Tsuchinshan-ATLAS at dawn on Sept. 21st over Swan Hill, Australia
“The comet was only 6 degrees above the horizon when I photographed it on Sept. 21st,” says Mattiazzo. “Using 15x70mm binoculars, I estimated its visual magnitude to be +3.9.”
This is very good news. Some astronomers predicted Comet Tsuchinshan-ATLAS would fall apart during its transit behind the sun. The fact that it is still intact and healthy means we could witness a bright naked-eye comet next month.
“Prospects remain excellent for a visually impressive evening display in mid-October,” says Qicheng Zhang of the Lowell Observatory. “Weather permitting, the entire Northern Hemisphere should be able to see Comet Tsuchinshan-ATLAS.”
Nick James of the British Astronomical Association just wrote an article anticipating the bright comet. “It makes its closest approach to Earth on October 12 when it will be 0.47 au away in the constellation of Virgo,” he says. “There is a possibility that the comet will be at a negative magnitude as it emerges into the evening sky from Oct. 10th onwards.”
Above: This light curve from astronomer Bum-Suk Yeom shows a huge spike in the comet’s brightness around Oct. 9-10. [more]
“Negative magnitude” means the comet could be visible in broad daylight, especially on Oct. 9th when light from the nearby sun will be forward scattered by comet dust, amplifying the comet’s brightness. “[Daylight photography of the comet] should only be attempted if you know what you are doing,” cautions James. “The sun will be very close by and this is potentially a very dangerous observation, similar to observing Venus at inferior conjunction.”
It’s been done before, though. Witness Comet McNaught in 2007, which was seen in broad daylight by thousands of observers. Could a repeat display be in the offing? Stay tuned for updates as Comet Tsuchinshan-ATLAS approaches Earth.
Aug. 6, 2024: Earth orbit is about to get a lot more crowded. On Aug. 6th, China launched the first 18 satellites of its new Thousand Sails megaconstellation. Sky watchers in the USA watched it happen as the the booster stage of the Long March rocket created a spectacular display across the Midwest:
“I did not see it in person,” says Dan Bush, of Albany, Missouri. “But my automated camera was monitoring the sky for Perseids. In the morning when I checked the footage for meteors, I discovered I had recorded this remarkable event.”
Pilot Alexander Goroshko of Westjet Airlines witnessed the display from a plane flying over Denver at 39,000 ft. “It looked amazing from the flight deck,” he says. Another pilot, Marc Livolsi, saw it twice over Ft. Dodge, Iowa, and one orbit later over Jackson, Wyoming.
The comet-like plumes are fuel dumped by the rocket booster as a safety precaution before re-entering Earth’s atmosphere. SpaceX does this all the time; their fuel dumps and deorbit burns frequently look like spirals because the rockets spin to release the Starlink satellites. This may be a case of a spiral viewed at an angle.
Thousand Sails is a Chinese initiative to compete with Starlink. Officials say that 108 satellites are planned for launch this year in separate batches of 36 and 54 satellites; another 500+ are planned for 2025. Ultimately the megaconstellation will contain more than 14,000 satellites (Starlink currently has about 6,200).
A Long March-6 rocket carrying 18 Thousand Sails satellites blasts off from the Taiyuan Satellite Launch Center in China’s Shanxi Province on Aug. 6, 2024.
Environmentalists have raised many concerns about Starlink including light-pollution of the night sky, a potentially hazardous traffic jam in low-Earth orbit, metallic contamination of the stratosphere, and even ozone depletion. Thousand Sails and a second proposed Chinese megaconstellation named “SatNet” (13,000 satellites) will only multiply these concerns.
Meanwhile, sky watchers have another phenomenon to track. If you photographed the Thousand Sails fuel dump, please submit your pictures here.
July 25, 2024: The biggest flare of Solar Cycle 25 just exploded from the farside of the sun. X-ray detectors on Europe’s Solar Orbiter (SolO) spacecraft registered an X14 category blast:
Solar Orbiter was over the farside of the sun when the explosion occured on July 23rd, in perfect position to observe a flare otherwise invisible from Earth.
“From the estimated GOES class, it was the largest flare so far,” says Samuel Krucker of UC Berkeley. Krucker is the principal investigator for STIX, an X-ray telescope on SolO which can detect solar flares and classify them on the same scale as NOAA’s GOES satellites. “Other large flares we’ve detected are from May 20, 2024 (X12) and July 17, 2023 (X10). All of these have come from the back side of the sun.”
Meanwhile on the Earthside of the sun, the largest flare so far registered X8.9 on May 14, 2024. SolO has detected at least three larger farside explosions, which means our planet has been dodging a lot of bullets.
The X14 farside flare was indeed a major event. It hurled a massive CME into space, shown here in a coronagraph movie from the Solar and Heliospheric Observatory (SOHO):
The CME sprayed energetic particles all over the solar system. Earth itself was hit by ‘hard’ protons (E > 100 MeV) despite being on the opposite side of the sun.
“This is a big one–a 360 degree event,” says George Ho of the Southwest Research Institute, principal investigator for one of the energetic particle detectors onboard SolO. “It also caused a high dosage at Mars.”
SolO was squarely in the crosshairs of the CME, and on July 24th it experienced a direct hit. In a matter of minutes, particle counts jumped almost a thousand-fold as the spacecraft was peppered by a hail storm energetic ions and electrons.
“This is something we call an ‘Energetic Storm Particle’ (ESP) event,” explains Ho. “It’s when particles are locally accelerated in the CME’s shock front [to energies higher than a typical solar radiation storm]. An ESP event around Earth in March 1989 caused the Great Quebec Blackout.”
So that’s what might have happened if the CME hit Earth instead of SolO. Maybe next time. The source of this blast will rotate around to face our planet a week to 10 days from now, so stay tuned. Solar flare alerts:SMS Text
July 12, 2024: Comet Tsuchinshan-ATLAS (C/2023 A3) is about to fall apart. It’s “inevitable,” according to a new study by astronomer Zdenek Sekanina. “Evidence suggests that the comet has entered an advanced phase of fragmentation,” he writes.
Above: Comet Tsuchinshan-ATLAS photographed by José J. Chambó
If true, this is disappointing news. Discovered in early 2023, the comet appears to be heading for a magnificent close encounter with the sun later this year, perhaps becoming as bright as Venus in October 2024. Instead, it could fall apart before it has a chance to become a naked-eye object.
Sekanina’s arguments are threefold: First, the comet has failed to brighten as it approaches the sun. Second, the comet’s orbit seems to be affected by a “non-gravitational acceleration.” This could happen if, say, inner jets are pushing apart a disintegrating nucleus. Third, the comet’s dust tail has an unusually narrow, teardrop shape with a peculiar orientation.
Together, these observations suggest a crumbling comet “in which increasing numbers of fractured refractory solids stay assembled in dark, porous blobs of exotic shape, becoming undetectable as they gradually disperse in space,” says Sekanina.
Above: This is what a break-up looks like–Comet LINEAR 24 years ago.
“That is a fascinating paper,” says Nick James, director of the Comet Section of the British Astronomical Association. “Sekanina is very well respected in the field, so it carries a lot of weight. To use ‘inevitable’ in any prediction about a comet may be unwise! But it is definitely a testable theory and another good reason to observe this comet at every opportunity.”
In fact, James isn’t convinced. In an independent data set, he finds no evidence of non-gravitational accelerations. “This doesn’t look like a comet that is fragmenting to me,” he says.
We’ll soon find out. The comet is brighter than 10th magnitude, well within range of mid-sized backyard telescopes, which means amateur astronomers can monitor the potential break-up. Point your optics here.
June 28, 2024: (Spaceweather.com) By the time you finish reading this story, there could be a new star in the night sky. Recurrent nova T CrB (pronounced “tee-core-bore”) is poised on the knife edge of a once-in-a-lifetime explosion.
“Our best estimate for the time of eruption is close to now,” says Brad Schaefer, Professor Emeritus of Astronomy at Louisiana State University.
Schaefer is a leading expert on T CrB. He’s been studying the star since he was a teenager. “When I was 18 year old, I calculated when T CrB should erupt again, and I’ve been waiting for this moment ever since,” he says.
T CrB is a “recurrent nova.” That means it erupts not just once, but over and over again. Its explosion in 1866 was the first nova astronomers had ever seen in detail. “No one knew what caused it,” says Schaefer. Another blast in 1946 established its period (79 or 80 years) and led researchers to the modern interpretation:
Located 3000 light years away, T CrB is a binary star system consisting of an ancient red giant circled by a hot white dwarf. Hydrogen from the red giant spills onto the surface of the white dwarf. It takes about 80 years to accumulate a critical mass, then–BOOM–a thermonuclear explosion occurs. “It’s an H-bomb that blows up on an incredibly large scale,” says Schaefer.
After an explosion, the process resets and repeats. Looking at old light curves, Schaefer realized that T CrB tells us when it’s about to explode. Approximately 1.1 years before each blow-up, there’s a “pre-eruption dip” in brightness. Amateur astronomers working with the American Association of Variable Star Observers (AAVSO) detected the pre-eruption dip in March 2023:
Above: The pre-eruption dip in March 2023
“If the star behaves in 2023-2024 as it did in 1945-1946, then the next eruption should take place in 2024.4+-0.3,” says Schaefer. “That’s May 2024 plus or minus a few months.”
The explosion will be visible to the naked eye. Schaefer expects it to be about as bright as the North Star (2nd magnitude). When it blows, T CrB will burst forth as an extra jewel in the “Northern Crown” (the constellation Corona Borealis), easy to find high in the summer night sky between Hercules and Bootes.
“T CrB will be the brightest nova for generations,” says Schaefer. “It’s a chance for everyone in the world to step outside, look up, and see the hellfire.”
Observing tips: (1) Tonight, go outside and see what Corona Borealis normally looks like: sky map. Then, when the nova explodes, you’ll be able to tell the difference. (2) Sign up for Space Weather Alerts. All subscribers (Basic and Pro) will receive an immediate text message when the nova explodes.
June 7, 2024: The night sky is about to get a new star. Sometime this summer, astronomers believe, a nova will explode in the constellation Corona Borealis (the Northern Crown). The exploding star will be bright enough to see with the naked eye even from light-polluted cities.
Above:A NASA artist’s concept of the T CrB binary star system
“It’s a once-in-a-lifetime event,” says Rebekah Hounsell of NASA’s Goddard Space Flight Center. “I believe it will create a lot of new astronomers out there.”
T Coronae Borealis (T CrB) is a binary system 3,000 light-years from Earth. It consists of a white dwarf orbiting an ancient red giant. Hydrogen from the red giant is being pulled down onto the surface of the white dwarf, accumulating toward a critical mass. Eventually, it will trigger a thermonuclear explosion.
The outburst will be brief. Once it erupts, the nova will be visible to the naked eye for a little less than a week – but Hounsell is confident it will be quite a sight to see. The expected magnitude is between +2 and +3, similar to stars in the Big Dipper.
“Typically, nova events are faint and far away,” says Elizabeth Hays, chief of the Astroparticle Physics Laboratory at NASA Goddard. “This one will be really close, with a lot of eyes on it. We can’t wait to get the full picture of what’s going on.”
April 10, 2024: This is starting to happen a lot in the state of Texas. On April 10th, around 2:14 in the morning, amateur astronomer Abdur Anwar looked up from Big Bend National Park and saw a glowing red blob glide across the starry sky. “I photographed it using my Google Pixel 6a phone in night mode,” he says.
“Is this a new aurora phenomenon?” he asks.
No, it’s SpaceX.
About 90 minutes before the red blob appeared, a Falcon 9 rocket lifted off from the Cape Canaveral Space Force Station in Florida, carrying 23 Starlink satellites to low-Earth orbit (Starlink Group 6-48). After the satellites were deployed, the rocket’s second stage executed a de-orbit burn, creating the nearly-spherical red light.
It’s not the first time sky watchers have noticed this phenomenon. “We are seeing 2 to 5 of them each month,” reports Stephen Hummel of the McDonald Observatory in Texas, who photographed a spectacular example last November.
The red glow is created by a chemical reaction. De-orbiting Falcon 9 rocket engines spray water (H2O) and carbon dioxide (CO2) into the upper atmosphere–as much as 400 lbs of exhaust gasses. A complicated series of charge exchange reactions between these molecules and O+ atoms produces red light at a wavelength of 6300 Å–coincidentally, the same color as red auroras.
Texas seems to be a great place to observe the phenomenon; most sightings have come from there or neighboring states. Texas is favored because, for Starlink missions launched from Florida, it’s approximately where a de-orbit burn will splash the rocket’s second stage safely into the South Atlantic. The burns happen about 90 minutes after launch–just when Anwar saw the blob.
Would you like to see one? Check the SpaceX schedule for night launches, then look at the sky 90 minutes after liftoff. Human eyes are not very sensitive to the 6300 Å wavelength of the red glow, but cameras have no such trouble. Take a short nighttime exposure and submit your images here.
May 23, 2024: (Spaceweather.com) Across the USA on May 10th and 11th, sky watchers marveled at bright displays of aurora borealis during the biggest geomagnetic storm in decades. Little did they know, something was also happening underfoot.
Strong electrical currents were surging through rocks and soil. The biggest voltages along the US eastern seaboard and in the Midwest were as much as 10,000 times normal. A map from NOAA and the US Geological Survey shows some of the ‘hot spots’ during the early hours of May 11th:
Back in March 1989, voltages only a little stronger than the ones shown above brought down the entire Hydro-Québec power system. The resulting Great Québec Blackout plunged millions of Canadians into darkness.
This time, however, power grids stayed up. “We haven’t heard of any serious problems so far,” reports Christopher Balch of NOAA’s Space Weather Prediction Center.
Balch leads an effort at NOAA to model geoelectric fields during solar storms. The map, above, is a snapshot from a real-time display that takes into account the 3D conductivity of the Earth and ongoing geomagnetic activity. A computer at the Space Weather Prediction Center crunches the data to produce minute-by-minute estimates of electricity in the ground.
When researchers talk about geoelectric fields they use units of volts per km (V/km). Earth’s crust naturally contains quiet-time fields measuring as little as 0.01 V/km. During geomagnetic storms, these values skyrocket.
“On May 10-11, geoelectric amplitudes exceeded 10 V/km in Virginia and 9 V/km in the upper Midwest,” says Jeffrey Love, a key member of the collaboration at the USGS. “These are very high. For comparison, we estimate that geoelectric amplitudes reached almost 22 V/km in Virginia during the March 1989 storm.”
This means the May 2024 storm was, electrically speaking, about half as intense as the storm that blacked out Québec 35 years ago. That’s too close for comfort. “Although power companies have taken measures to improve the resilience of their systems, no one would welcome another storm as intense as that of March 1989,” says Love.
Realtime electric field maps are published 24/7 on the NOAA website. During the next geomagnetic storm, click here to see what’s happening underfoot!
May 16, 2024: On the south Pacific island of New Caledonia, no one expects to see auroras. Ever. Situated about halfway between Tonga and Australia, the cigar-shaped island is too close to the equator for Northern or Southern Lights. Yet on May 10, 2024, this happened:
“I have rarely been so happy when taking a photo!” says Frédéric Desmoulins, who photographed the display from Boulouparis in the island’s south province. “I could see the red color of the auroras with my naked eye. According to the New Caledonian Astronomy Society, these photos are the first for this territory.”
“The auroral visibility from New Caledonia is really unique and extremely valuable,” says Hisashi Hayakawa, a space weather researcher at Japan’s Nagoya University. “As far as we know, the last time sky watchers saw auroras in the area was during the Carrington Event of Sept. 1859, when auroras were sighted from a ship in the Coral Sea.”
Hayakawa specializes in historical studies of great auroral storms. He tries to go back in time as far as possible. The problem is, magnetometers and modern sensors didn’t exist hundreds or thousands of years ago. Instead, he looks for records of aurora sightings in old newspapers, diaries, ships logs, even cuneiform tablets. Great Storms are identified by their low latitude–anything with naked-eye auroras below 30° MLAT (magnetic latitude).
“May 10th was definitely a Great Storm,” declares Hayakawa. “Naked-eye auroras sightings in New Caledonia (MLAT = -26.4°) and Puerto Rico (MLAT = 27.2°) confirm this in both hemispheres.”
In fact, it is among the top 20 Great Storms of the past 500 years. The above timeline from a research paper by Hayakawa has been modified to display the May 10th event. It is the green dot on the far-right end of the timeline.
This isn’t just an arcane historical curiosity. “We need to know about Great Storms of the past to understand how big storms might become today,” explains Hayakawa. “Our modern technological society depends upon it.”
Readers, if you witnessed auroras at low latitudes on May 10th, please submit your photos to our gallery and fill out this questionnaire from Hayakawa. Your observations may be included in a future research paper about this extreme storm.
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