Oct. 29, 2021: Imagine waking up to this headline: “Half of Earth’s Satellites Lost!” Impossible?  It actually happened on an October day in 2003.

Turn back the clock 18 years. Solar Cycle 23 was winding down, and space weather forecasters were talking about how quiet things would soon become when, suddenly, the sun unleashed two of the strongest solar flares of the Space Age. The first, an X17-category blast on Oct. 28, 2003, hurled this CME directly toward Earth:

Traveling 2125 km/s (almost 5 million mph), the cloud slammed into Earth’s magnetic field only 19 hours later, sparking an extreme (G5) geomagnetic storm. The storm had barely begun when the sun erupted again. An X10-flare on Oct. 29th created another CME traveling almost as fast, 1948 km/s. It also arrived in 19 hours. The one-two punch kept the geomagnetic storms going for almost three full days–Oct. 29, 30, and 31, 2003.

Researchers named them “the Halloween Storms.” Modern accounts of the event tend to focus on auroras. Northern Lights descended as far south as Georgia, California, New Mexico, Arizona, Texas, and Oklahoma: photo gallery.

But auroras were just the tip of the iceberg. High energy particles accelerated by the CMEs rifled toward Earth, peppering our planet’s atmosphere with protons and electrons. Onboard the International Space Station, astronauts took shelter in the hardened Zvezda service module. Hundreds of miles below, airline pilots were changing course. Almost every flight over Earth’s poles detoured to lower latitudes to avoid radiation, costing as much as $100,000 per flight. Many Earth-orbiting satellites experienced data outages, reboots and even unwanted thruster firings. Some operators simply gave up and turned their instruments off. Goddard’s Space Science Mission Operations Team estimates that 59% of NASA’s Earth and space science satellites were affected in one way or another.

There’s a dawning awareness that something else important happened, too. Many of Earth’s satellites were “lost.”

In a 2020 paper entitled “Flying Through Uncertainty,” a team of researchers led by Thomas Berger at the University of Colorado’s Space Weather Technology, Research, and Education Center report some little-known recollections from USAF satellite operators. During the Halloween storms, they recalled, “the majority of [low Earth orbiting] satellites were temporarily lost, requiring several days of around-the-clock work to reestablish [their positions].”

Satellites often go course during geomagnetic storms, but this was extreme.

“The Halloween storms pumped an extra 3 Terrawatts of power into Earth’s upper atmosphere¹,” explains Martin Mlynczak, principal investigator of NASA’s SABER spacecraft, which measured the energy dump. “We didn’t feel it down on the planet’s surface, but it was a big event for Earth orbiting satellites. The extra power puffed up the atmosphere, sharply increasing aerodynamic drag.”

Simulations show that even moderate geomagnetic storms can shift the expected position of a satellite by 10 km or more. The Halloween storms created far larger uncertainties with the potential for collisions. United States Space Surveillance Network radars and telescopes worked urgently to find everything again.

Not knowing where satellites are is a problem mainly because of collisions. There are thousands of objects in Earth orbit ranging from billion-dollar active satellites to worthless nuts and bolts. Satellites are routinely maneuvered to avoid predicted collisions–but you can’t avoid a collision when you don’t know where you are.

“Fortunately, the Halloween storm did not cause any major collisions that we know of,” write Berger and his co-authors. “But if a geomagnetic storm on the level of the 2003 event were to occur today, the situation could be very different. Most satellite operators today have never experienced anything like the Halloween 2003 storm, and there are now (in 2020) more than 1,700 operational satellites and at least 19,400 pieces of debris larger than 10 cm in low Earth orbit.”

A number of countries and corporations are planning mega-constellations (Starlink is the most famous), which could ultimately swell the satellite population to 65,000 or more. Losing track of satellites in such a congested environment could theoretically trigger a cascade of collisions, rendering low Earth orbit unusable for years following an extreme geomagnetic storm.

Now that’s scary.

End notes:

1. Martin Mlynczak provides some context:”While 3 Terawatts sounds like a lot of power (and it is!), averaged over the area of the Earth it is 6 milliwatts per square meter. The global average outgoing infrared radiation from the entire planet and atmosphere below 100 km is 240 watts per square meter.”
2. For more information about the Halloween Storms, check out this excellent summary from NOAA.

Oct. 24, 2021: Something does not add up. New sunspot AR2887 has two primary cores, each about the size of Earth. Usually when a sunspot looks like this, the two cores have opposite magnetic polarities, positive (+) and negative (-). In this case, however, they’re the same.

Pictured above is a magnetic map of AR2887 from NASA’s Solar Dynamics Observatory. It shows the primary poles of double sunspot AR2887 are both negative (-). Surrounding patches of positive (+) magnetic flux provide balance.

Perhaps AR2887 is not one but actually two sunspots jammed together in close proximity. We’ll get a better view of its magnetic architecture as AR2887 turns toward Earth in the days ahead. Stay tuned. Solar flare alerts: SMS Text.

more images: from Cai-Uso Wohler of Bispingen, Lueneburg Heath, Germany; from Francois Rouviere of Cannes, France; from Richard Jaworski of Carlingford, NSW, Australia; from Maximilian Teodorescu of Magurele, Romania;

Oct. 21, 2021: Paolo Bardelli will never forget Oct. 21, 2001. “The sky over my hometown in Italy suddenly filled with intense red auroras,” he recalls. “This happened exactly 20 years ago today.”

A trip down memory lane: In 2001, Solar Cycle 23 was peaking and solar activity was very high. Strong flares were a daily occurance. On Oct. 19th, giant sunspot AR9661 erupted twice in quick succession, producing almost identical X1.6-class solar flares. The double blast hurled two bright CMEs toward Earth: CME #1, CME #2.

This is what the sun looked like that day:

The first CME took only two days to reach Earth. It was fast and potent. The storm cloud’s arrival on Oct. 21, 2001, ignited a severe geomagnetic storm (Kp=8). Solar wind speeds in the CME’s wake topped 700 km/s, keeping the storm going for more than 15 hours.

In Troutman, North Carolina, Ronnie Sherril witnessed the CME’s impact. “Auroras were visible in twilight even before the evening sky faded to black,” says Sherril, who took this picture at 7:30 pm local time:

“By 10:30 pm the sky had exploded into bright red with yellowish beams,” says Sherril. “What an awesome display!”

Less than a day later the second CME arrived, and it happened all over again. Another 15 hours of strong-to-severe storming ensued. Using data from a global network of magnetometers, NOAA made this record of planetary K-indices during the two-day event:

Red auroras were sighted in Germany, France, Italy, Spain, Australia, Japan, and in the United States as far south as latitude 35N. Remarkably, there were no widespread power outages or satellite disruptions. The Internet functioned normally throughout. It was mainly an aurora show.

Some observers are ready for more. “We are hoping for something similar for Solar Cycle 25, as the sun has recently had a good increase in its activity,” says Bardelli. Indeed, young Solar Cycle 25 is intensifying, but Solar Max isn’t expected for another 3 to 4 years. Until then, browse the October 2001 Aurora Photo Gallery.

Oct. 14, 2021: So you think you know what a comet is? Think again. Comet 29P/Schwassmann-Wachmann is challenging old ideas. Astronomers call it a comet, but, really, “giant space volcano” might be a better description. It’s a 60-km-wide ball of ice orbiting the Sun beyond Jupiter, and it appears to be one of the most volcanically active bodies in the entire Solar System.

Comet 29P just blew its top … again. In late September 2021, 29P erupted 4 times in quick succession, blowing shells of “cryomagma” into space. Arizona amateur astronomer Eliot Herman has been monitoring the debris:

“Initially it looked like a bright compact object,” says Herman. “Now the expanding cloud is 1.3 arcminutes wide (bigger than Jupiter) and sufficiently transparent for background stars to shine through.”

When this object was discovered in 1927, astronomers thought they had found a fairly run-of-the-mill comet, unusual mainly because it was trapped in a nearly circular orbit between Jupiter and Saturn. 29P quickly proved them wrong as it began to erupt over and over again. Modern observations show that outbursts are happening as often as 20 times a year (almost 3 times the rate of the widely-quoted Wikipedia figure, 7.3 times per year).

“The current outburst, which began on Sept. 25th, appears to be the most energetic of the past 40 years,” says Dr. Richard Miles of the British Astronomical Association (BAA). “Within a span of only 56 hours, four eruptions took place in quick succession, creating a ‘superoutburst.'”

Miles is a leading researcher of 29P, and he has developed a theory to explain what’s happening. The “comet,” he believes, is festooned with ice volcanoes. There is no lava. The “magma” is a cold mixture of liquid hydrocarbons (e.g., CH₄, C₂H₄, C₂H₆ and C₃H₈) akin to those found in the lakes and streams of Saturn’s moon Titan. In Miles’s model, the cryomagma contains a sprinkling of dust and it is suffused with dissolved gases N₂ and CO, all trapped beneath a surface which, in some places, has the consistency of wax. These bottled-up volatiles love to explode when a fissure is opened–hence some of 29P’s more spectacular eruptions.

In a seminal paper published 5 years ago, Miles studied the modern record of eruptions and he found some patterns. Data suggest that 29P rotates every 57.7 days. The most active vents are concentrated on one side of the ice-ball in a range of longitudes less than 150 degrees wide. At least 6 discrete sources have been identified.

While most outbursts fade within a week or so, this superoutburst is still visible. The rat-a-tat-tat eruption in September boosted the comet’s brightness 250-fold, and it hasn’t declined much since then. With an integrated magnitude between +10 and +11, the expanding cloud is well within the range of backyard telescopes.

“Comet 29P can be seen with an 8 inch ‘scope,” says Herman. “In smaller instruments it will appear to be a bright dot. To resolve the cloud and photograph individual stars shining through it, I used the big half-meter iTelescope T11.”

Ready see something weird? 29P is located in the constellation Auriga, easy to find high in the sky at midnight. Visit Sky&Telescope for observing tips. Also, for the latest news check out the BAA’s MISSION 29P website.

Oct. 12. 2021: It’s been a while. Last night, auroras were sighted in more than a dozen US states after a CME struck Earth’s magnetic field. “The G2 geomagnetic storm produced the first visible auroras from coastal Massachusetts since 2017,” reports Chris Cook, who snapped this 30-second self portrait around 1am EDT on Oct. 12th:

The red-topped auroras Cook witnessed are relatively rare; they appear during geomagnetic storms that spread far from the poles. Red is caused by oxygen atoms meeting the solar wind as high as 500 km above Earth’s surface.

In some states the auroras were so bright onlookers photographed them using nothing more than their cell phones. iPhone or Android? You decide:

The iPhone photo on the left comes from Tyler Knight of Mound, Minnesota, while the Samsung Galaxy image on the right was taken by meteorologist James Sinko on Castle Hill, Maine. Across the border in Saskatoon, Canada, Frank Lang recorded a must-see video using his iPhone 12.

At the apex of the storm, auroras descended as far south as Nebraska. Caryl Bohn photographed their faint red glow from the town of West Oak.

Subscribers to our Space Weather Alert system were notified the instant the CME hit. The alert was triggered by a sudden uptick in solar wind speed signalling the arrival of a shock front:

The plot shows data from NOAA’s DSCOVR spacecraft. When the CME passed by, the solar wind quickened by 120 km/s. At the same time, the plasma density tripled, and the temperature increased almost 10-fold. These are classic signs of a direct hit by a CME.