AURORAS AS TIME MACHINES: The
fall of 1770 was not a good time for Capt. James Cook and the
crew of the HMS Endeavour. One year earlier, they successfully
observed the transit of Venus from Tahiti. Many aboard would rue
leaving that paradise. After a violent stop in New Zealand, Endeavour
struck Australia's Great Barrier Reef, tearing a massive hole in
her hull and beaching the vessel for 7 weeks for repairs. By the
time the ship was underway again, many of the crew were suffering
from tropical diseases, malnutrition, and exhaustion.
That's when the geomagnetic storm struck.
Endeavour was sailing near Timor Island (latitude -9.9o)
on Sept. 16, 1770, when red auroras appeared in the night sky.
The expedition's naturalist Joseph A. Banks and his assistant Sydney
Parkinson both noted the event
in their logs, although they were unsure what they had seen. The
idea that auroras could spread to within 10 degrees of the
equator seemed outlandish.
Yet auroras they were. A 2017 study
led by Hisashi Hayakawa established that Cook's auroras were
part of an extreme 9-day display across China, Japan, and
Southeast Asia. Some of the lights were "as bright as a full Moon."
Clearly,
the "Cook Event" was a big deal. But how big? Researchers have long
wondered. Magnetometers were only invented in the 19th century,
so there are no scientific measurements of geomagnetic activity
before then. Rating old storms has been a matter of guesswork.
Right: Joseph Banks' 1770 aurora log entry.
A study published in the April 2025 edition of Space Weather may have solved this problem by turning auroras into time machines.
In their paper,
Jeffrey Love of the US Geological Survey and colleagues analyzed 54
geomagnetic storms from 1859 to 2005, using both magnetometer data and
overhead aurora sightings. By correlating the two, they developed a
statistical model that lets researchers estimate the strength of
historical storms based on eyewitness accounts—no magnetometer required.
One of the key findings of their study is
that Cook's storm was (within the margin of error) the same size as
the famous Carrington Event of 1859. They also found a very big
storm just a few days before the Carrington Event. On
August 28, 1859, there were no magnetometer data available
because it was Sunday, a day off for observatory staff.
However, auroras were reported overhead in Havana, Cuba. Love's model
pegged that storm at ~two-thirds of the Carrington Event,
making it one of the biggest geomagnetic storms on record.
The good news for Cook and his crew:
They weren't using modern technology like radio or GPS, which
might have failed. Cook had no trouble navigating the magnetic storm.
If it happened again today, we might not be so lucky.
A HIDDEN WORLD OF SOLAR ACTIVITY: In
the 17th century when Anton van Leeuwenhoek looked through a microscope
and saw bacteria for the first time, he revealed a new "world of the
small" and forever upended the field of biology. Is the same thing
about to happen to solar physics?
Maybe. A paper just published in Nature Astronomy
reports a new technology for seeing very small things in the
atmosphere of the sun. It's a system of adaptive optics that corrects
for turbulence in Earth's atmosphere. A test run in July 2023 on the
1.6 m Goode Solar Telescope in California's Big Bear Lake produced an
immediate discovery:
"We became astounded witnesses to a
strange, short-lived object," recalls the research team, led by
Dirk Schmidt of the NSF National Solar Observatory. "We call it a
twisted plasmoid."
The plasmoid is unlike anything seen inside the sun's atmosphere before. NASA's Solar Dynamics Observatory was observing at the same time
and saw nothing. The Big Bear adaptive optics system is so good
at correcting turbulent blur, it outperforms space telescopes.
A movie of the plasmoid shows a narrow
stream of plasma less than 100 km wide moving like a flagellate under
van Leeuwenhoek's microscope. The front of the stream "suddenly stopped
and collided with its own rear half," before fading away. Other
structures observed by the team may be as narrow as 20 km across.
The
1.6-meter Goode Solar Telescope in Big Bear Lake. The steady
temperature of the water surface helps keep the air around the telescope
calm
It's not clear whether this is a
significant discovery or just something idiosyncratic and weird.
We'll soon find out. The researchers plan to install the same
system on the giant Daniel K. Inouye Solar Telescope
in Hawaii, where adaptive optics on its 4-meter mirror could
reveal an even greater menagerie. Let the plasmoid hunt begin!
For more images from the new adaptive optics system, click here.
MOON RINGS -- 'AUREOLES' VS. 'CORONAS': Sometimes
the best thing about a bright full Moon is what
goes on around it. Last night in Pennsylvania, Dave Mitsky
photographed this beautiful moon-ring:
The
correct name is "lunar aureole," cousin to the
better-known lunar corona. Aureoles and coronas are caused
by water droplets in clouds. When the droplets are a jumble
of different sizes, they produce a straw-colored
ring--an aureole. When the droplets are all of the same size
they produce a rainbow-colored ring--a corona. Look for both tonight.
MINOR GEOMAGNETIC STORM WATCH: Another solar wind stream is heading for Earth. It is flowing from a canyon-like hole in the sun's atmosphere. First contact with the stream on Feb. 14th could cause a minor G1-class geomagnetic storm with Arctic auroras for Valentine's Day.
POLAR STRATOSPHERIC CLOUDS AT NIGHT: Unusual
weather in the stratosphere has set the stage for a rare nighttime
apparition of polar stratospheric clouds (PSCs). Marianne Bergli
photographed the display last night in Kilpisjervi, Finland:
"The PSCs were even more colorful than auroras," says Bergli. "The full Moon lit them beautifully."
This is rare. Normally, Earth's stratosphere has no clouds at all. Only when the temperature drops to a staggeringly-low -85 C can widely-spaced water molecules assemble into icy Type II
PSCs. During a typical polar winter, sky watchers might see them no
more than once or twice, almost always during the day when bright
sunlight causes their colors to blossom.
Nighttime displays are doubly
rare because the clouds must coincide with a bright Moon to make them
visible in full color. Tonight is such a night!
"I have seen more PSCs this
winter than I have seen before in all my life," says Fredrik Broms of
Kvaløya, Norway, a well-known aurora photographer who has been carefully
watching the Arctic sky for decades. This is what he saw on Feb. 11th:
"The PSCs were truly amazing," he says. "Since mid-January 2025, I have seen these colorful clouds weekly or every second week."
According to NASA's MERRA2 climate model, the polar stratosphere has been exceptionally cold this winter with temperatures dropping to near 45-year lows. The reason might be the stratospheric polar vortex. This winter's vortex has been strong, keeping cold air bottled up over the Arctic Circle.
Springtime dynamics could soon
upset that cold air mass. Until then, Arctic sky watchers should remain
alert for PSCs--even at night. They're the most beautiful clouds on
Earth.
A HOLE IN THE SUN'S ATMOSPHERE: A large hole in the sun's atmosphere is directly facing Earth and blowing a stream of solar wind in our direction. Estimated time of arrival: Feb. 1st. Minor G1-class geomagnetic storms are possible when the gaseous material reaches Earth.
A WARNING FROM THE TREES:How
bad can a solar storm be? Just ask a tree. Unlike human records, which
go back hundreds of years, trees can remember solar storms for
millennia.
Nagoya University doctoral student Fusa
Miyake made the discovery in 2012 while studying rings in the stump of a
1900-year-old Japanese cedar. One ring, in particular, drew her
attention. Grown in the year 774–75 AD, it contained a 12% jump in
carbon-14 (14C), an isotope created by cosmic radiation. The surge was
20 times greater than ordinary fluctuations in cosmic rays. Other teams
confirmed the spike in wood from Germany, Russia, the United States,
Finland, and New Zealand. Whatever happened, trees all over the world
experienced it.
Most researchers think it was a solar storm—an extraordinary one. Often, we point to the Carrington Event of 1859
as the worst-case scenario for solar storms. The 774-75 AD storm was
at least 10 times stronger; if it happened today, it would floor modern
technology. Since Miyake's initial discovery, she and others have
confirmed four more examples (7176 BC, 5259 BC, 664-663 BC, 993 AD).
Researchers call them "Miyake Events."
It's not clear that all Miyake Events are
caused by the sun. Supernova explosions and gamma-ray bursts also
produce carbon spikes. However, the evidence tilts toward solar storms.
For each of the confirmed Miyake Events, researchers have found
matching spikes of 10Be and/or 36Cl in ice cores. These isotopes are
known to trace strong solar activity. Moreover, the 774-75 AD Miyake
Event had eyewitnesses; historical reports of auroras in China and England suggest the sun was extremely active around that time.
Miyake Events have placed
dendrochronologists (scientists who study tree rings) in the center of
space weather research. After Miyake’s initial discovery in 2012, the
international tree ring community began working together to look for
evidence of solar superstorms. Their collaboration is called "the
COSMIC initiative." COSMIC results published in a 2018 edition of Nature confirm that Miyake Events in 774-75 AD and 993 AD were indeed global. Trees on five continents recorded carbon spikes.
"There could be additional Miyake Events throughout the Holocene"
says Irina Panyushkina, a member of the COSMIC initiative from the
University of Arizona's Laboratory for Tree-Ring Research. "Finding them
will be a slow and systematic process."
Above: A global map of COSMIC tree ring and ice core measurements [more]
"An important new source for annual 14C measurements are floating tree-ring records
from Europe and the Great Lakes," says Panyushkina. "These are very old
rings that could potentially capture 14C spikes as far back as 15,000
years. Eventually, I believe we will have a complete record of Miyake
Events throughout that period."
Four more candidates for Miyake Events have recently been identified (12,350 BC, 5410 BC, 1052 C, and 1279 C). The candidate in 12,350 BC,
identified from tree rings the French Alps, may be more than twice the
size of any other Miyake Event. Confirmation requires checking trees on
many continents and finding matching spikes of 10Be and 36Cl in ice
cores.
A complete survey of Miyake Events could
tell us how often solar superstorms occur and how much peril the sun
presents to a technological society. Stay tuned for updates from the
trees.
SOLAR STORMS ARE DRIVING FARMERS CRAZY: Planting
season is a hectic time for farmers. For many, it means working
through the night using GPS-guided tractors to plant thousands of
acres in a short period of time. The season was in full swing on
May 10, 2024, when the biggest solar storm in decades struck
Earth.
"Our tractors acted like they
were demon possessed," says Elaine Ramstad, a Spaceweather.com
reader and aurora chaser who helps out on a family farm in
Northern Minnesota. "All my cousins called me during the May 10th
storm to tell me that 'my auroras' were driving them crazy while
they were planting."
Northern Lights over the Ramstead family beet farm on May 10, 2024
Modern farmers rely heavily on
GPS. Guided by satellites, smart tractors can work around the
clock, seeding perfectly straight rows with precise amounts of
seed and fertilizer. When harvesting time comes, the tractors can
return to exactly the same spots to pick the crops.
This kind of precision
agriculture has become widespread. "I would guess 80% or more of all
farmers in the Midwest use at least basic GPS for
something--whether it's auto-steer or yield mapping," says Ethan
Smidt, a service manager for John Deere. "At least 50% of all
farmers are VERY reliant on GPS and use it on every machine all
year long."
Solar activity poses a growing problem for farm-tech. During big solar storms, a layer of Earth's atmosphere called "the ionosphere" fills with bubbles, waves, and turbulence,
which severely distort radio signals from GPS satellites. tractors and harvesters can't lock on, which stops them in their
tracks. Or the signal may be garbled, causing them to juke back and
forth.
Crooked rows in Iowa caused by a solar storm.
May 10th wasn't the end of it. Tractors went off-course again during the autumnal storms of Oct. 6th and 10th.
Ramstad was helping her
cousins defoliate sugar beets on Oct. 6th when her tractor
started acting up: "As the aurora activity began, my GPS was off
by close to a foot. Twice while on Autosteer, the tractor danced a
row to the left, to the right — and then the defoliator was off a
row, so I had to loop around and start over. By
nightfall, there was no controlling the Autosteer."
Indiana farmer Michael Spencer
had a similar experience: "This fall was the first time I was
able to see the aurora. My hair was standing on end from the
beauty, however, it did make the John Deere tech dance. When the
storms were strongest around Oct. 7th, my tractor's Autosteer
system would 'jump the line'--meaning, the tractor would make a
quick jolt left or right and I would have to manually reset."
A beet defoliator--an example of massive hardware thrown off course by solar activity.
It doesn't take an historic solar storm to cause problems. While the May 10th storm was a rare and extreme category G5, storms in October were much more common category G3 and G4 events. All of them sent massive pieces of hardware off course.
NASA says that Solar
Maximum has arrived, and it could last for another 1 to 2 years,
confusing tractors again in 2025 and 2026. Stay tuned for more crooked
rows. Solar storm alerts:SMS Text
BLACK AURORAS OVER ALASKA: Todd
Salat is a veteran photographer of auroras in Alaska. For years he has
chased the lights and seen most of what Mother Nature has to offer. But
even he was puzzled on Nov. 22nd when these strangely-shaped auroras
appeared overhead:
"I saw these bizarre auroras
drift over southcentral Alaska around 4 am last Friday morning," says
Salat. "It came up from the northwest and I was like, whoa! It looked
like the letter E to me."
Salat may have witnessed an episode of 'black auroras.' They are dark rings or black blobs that sometimes appear in an otherwise ordinary expanse of auroral light. For example, look at Figure 1 in this research paper on the topic. Some researchers call them "anti-auroras." The black auroras in Salat's photo are circled here.
Ordinary auroras are caused by electrons
raining down from space. Black auroras are the opposite. Instead of
electrons raining down, electrons are propelled upwards back into
space. Europe's fleet of Cluster spacecraft flew over a black aurora on
Jan. 14, 2001, and saw the process in action:
Sensors onboard the spaceraft detected
strong positive electric fields in the black aurora zone. These fields
reversed the normal downward rain of aurora-causing electrons.
The study of black auroras is
still in its infancy, and forecasters cannot yet predict when or where
they might appear. Aurora watchers, the next time a geomagnetic storm
erupts, be alert for black.
March 13, 2021: They call it “the day the sun
brought darkness.” On March 13, 1989, a powerful coronal mass ejection
(CME) hit Earth’s magnetic field. Ninety seconds later, the Hydro-Québec
power grid failed. During the 9 hour blackout that followed, millions
of Quebecois found themselves with no light or heat, wondering what was going on?
“It was the biggest geomagnetic storm of the Space Age,” says Dr.
David Boteler, head of the Space Weather Group at Natural Resources
Canada. “March 1989 has become the archetypal disturbance for
understanding how solar activity can cause blackouts.”
It seems hard to believe now, but in 1989 few people realized solar
storms could bring down power grids. The warning bells had been ringing
for more than a century, though. In Sept. 1859, a similar CME hit
Earth’s magnetic field–the infamous “Carrington Event“–sparking
a storm twice as strong as March 1989. Electrical currents surged
through Victorian-era telegraph wires, in some cases causing sparks and
setting telegraph offices on fire. These were the same kind of currents
that would bring down Hydro-Québec.
“The March 1989 blackout was a wake-up call for our industry,” says
Dr. Emanuel Bernabeu of PJM, a regional utility that coordinates the
flow of electricity in 13 US states. “Now we take geomagnetically
induced currents (GICs) very seriously.”
What are GICs? Freshman physics 101: When a magnetic field swings
back and forth, electricity flows through conductors in the area. It’s
called “magnetic induction.” Geomagnetic storms do this to Earth itself.
The rock and soil of our planet can conduct electricity. So when a CME
rattles Earth’s magnetic field, currents flow through the soil beneath
our feet.
Above: Grey areas indicate regions of igneous rock where power grids are most vulnerable to geomagnetic storms.
Québec is especially vulnerable. The province sits on an expanse of
Precambrian igneous rock that does a poor job conducting electricity.
When the March 13th CME arrived, storm currents found a more attractive
path in the high-voltage transmission lines of Hydro-Québec. Unusual
frequencies (harmonics) began to flow through the lines, transformers
overheated and circuit breakers tripped.
After darkness engulfed Quebec, bright auroras spread as far south as Florida, Texas, and Cuba. Reportedly,
some onlookers thought they were witnessing a nuclear exchange. Others
thought it had something to do with the space shuttle (STS-29), which
remarkably launched on the same day. The astronauts were okay, although
the shuttle did experience a mysterious problem with a fuel cell sensor
that threatened to cut the mission short. NASA has never officially
linked the sensor anomaly to the solar storm.
Much is still unknown about the March 1989 event. It occurred long
before modern satellites were monitoring the sun 24/7. To piece together
what happened, Boteler has sifted through old records of radio
emissions, magnetograms, and other 80s-era data sources. He recently
published a paper in the research journal Space Weather summarizing his findings — including a surprise:
“There were not one, but two CMEs,” he says.
The sunspot that hurled the CMEs toward Earth, region 5395, was one
of the most active sunspot groups ever observed. In the days around the
Quebec blackout it produced more than a dozen M- and X-class solar
flares. Two of the explosions (an X4.5 on March 10th and an M7.3 on
March 12th) targeted Earth with CMEs.
“The first CME cleared a path for the second CME, allowing it to
strike with unusual force,” says Boteler. “The lights in Québec went out
just minutes after it arrived.”
Above: Auroras over Pershore, England, during the March 13, 1989, geomagnetic storm. Credit: Geoffrey Morley.
Among space weather researchers, there has been a dawning awareness
in recent years that great geomagnetic storms such as the Carrington
Event of 1859 and The Great Railroad Storm of May 1921
are associated with double (or multiple) CMEs, one clearing the path
for another. Boteler’s detective work shows that this is the case for
March 1989 as well.
The March 1989 event kicked off a flurry of conferences and
engineering studies designed to fortify grids. Emanuel Bernabeu’s job at
PJM is largely a result of that “Québec epiphany.” He works to protect
power grids from space weather — and he has some good news.
“We have made lots of progress,” he says. “In fact, if the 1989 storm
happened again today, I believe Québec would not lose power. The modern
grid is designed to withstand an extreme 1-in-100 year geomagnetic
event. To put that in perspective, March 1989 was only a 1-in-40 or 50
year event–well within our design specs.”
Some of the improvements have come about by hardening equipment.
For instance, Bernabeu says, “Utilities have upgraded their protection
and control devices making them immune to type of harmonics that brought
down Hydro-Québec. Some utilities have also installed series capacitor
compensation, which blocks the flow of GICs.”
Other improvements involve operational awareness.
“We receive NOAA’s space weather forecast in our control room, so we
know when a storm is coming,” he says. “For severe storms, we declare
‘conservative operations.’ In a nutshell, this is a way for us to
posture the system to better handle the effects of geomagnetic activity.
For instance, operators can limit large power transfers across critical
corridors, cancel outages of critical equipment and so on.”
The next Québec-level storm is just a matter of time. In fact, we
could be overdue. But, if Bernabeu is correct, the sun won’t bring
darkness, only light.
👇👇👇👇TODAY:
CME IMPACT: A CME struck Earth today, July 25th, at 1422 UT. We're not sure, but this could be the halo CME launched toward Earth by a dark plasma eruption on July 21st. G1-class geomagnetic storms are possible in the hours ahead as Earth moves through the CME's magnetized wake. CME impact alerts:SMS Text
MAJOR FARSIDE SOLAR FLARE:
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
Right: Joseph Banks' 1770 aurora log entry. 
