Oct. 25, 2023 (Spaceweather.com): When Solar Cycle 25 began in 2020, leading forecasters thought it would be weak and slow to develop. Fast forward three years: NOAA is now predicting a quicker, stronger solar cycle. The revised forecast, published yesterday, shows Solar Max coming sometime between January and October 2024:
NOAA’s original prediction for Solar Cycle 25 is shown in pink (), the broad band indicating the uncertainty of the forecast. It has become clear in recent years that the original prediction was too low, which prompted NOAA to issue a new one. The magenta line () traces the new forecast, and takes into account recent high sunspot counts.
Uncertainties in the new forecast are bounded by different shades of magenta. There is roughly a 25% chance that the smoothed sunspot number will fall within the dark-shaded region; a 50% chance it will fall in the medium-shaded region; and a 75% chance it will fall in the lightest of the shaded regions.
If this new forecast is correct, Solar Cycle 25 could land in the ballpark of Solar Cycle 23, which peaked in 2000-2001, and produced the famous Halloween Storms of 2003. However, the odds still favor Solar Cycle 25 being a bit weaker than Solar Cycle 23. Either way, next year’s Solar Max could be potent.
NOAA plans to update this new forecast every month. Check out their Space Weather Prediction Testbed for the latest prediction.
Oct. 23, 2023: (Spaceweather.com) A recent display of auroras over Canada has experts scratching their heads. The mystery? They were orange:
“This was a first for me,” says Harlan Thomas, who photographed the display over Sibbald Pond west of Calgary, Alberta, on Oct. 19th. “The orange was sublime, just incredible. The pillars in the center stayed there glowing for more than 20 minutes.”
Auroras aren’t supposed to be orange. Consider the following: Auroras get their colors from atoms and molecules in Earth’s atmosphere. During geomagnetic storms, energetic particles rain down from space, striking the air and causing it to glow. Red, green, purple and even pink are common signs of excited oxygen and nitrogen.
The problem is, there’s nothing in the air capable of making bright orange. Theoretically, nitrogen and oxygen (N2, N2+, and O2+) can produce emissions at orange wavelengths. However, these emissions are very weak compared to other colors produced by the same molecules. Any orange should be overwhelmed.
Aurora colors produced by atoms and molecules in Earth’s atmosphere. [more]
The answer may be hiding in plain sight. Take another look at Thomas’s photo. Bright red auroras appear on top, overlapping green auroras lower down. Red and green mixing together may have produced the yellow-orange glow.
Indeed, aurora physicist Kjellmar Oksavik of the University of Bergen in Norway believes that’s the correct explanation:
“Red auroras are formed by low-energy electrons colliding with atomic oxygen at high altitudes (200-400 km). Here, oxygen atoms are excited into a quantum state called O(1D), where they can emit a red photon at 630.0 nanometers,” Oksavik says.
“Green auroras are formed by higher-energy electrons penetrating deeper and colliding with atomic oxygen at lower altitudes (100-150 km),” he continues. “Here, oxygen atoms are excited into a state called O(1S), where they emit a green photon at 557.7 nanometers.”
“In between, there can be a mixing of the two processes, which fools the camera and eye to believe that it is orange. In reality, it is both red and green at the same time,” he says.
More examples of orange recorded during the Halloween Storms of 2003. Credit: Jay Edwards [more]
Oksavik points out one more thing in Harlan Thomas’s photo: “It beautifully reveals the alignment of Earth’s magnetic field. The bright pillar in the center is a textbook example of a very tall auroral ray. These are aligned along the magnetic field and caused by a broad energy spectrum of electrons [raining down from space]. Slower electrons collide high up (red light), while more energetic electrons travel further down into a much denser atmosphere (green light).” The overlap naturally produces a yellow-orange glow–no mystery molecule required.
Oct. 18, 2023: In a quiet room, you can hear a pin drop. Norwegian citizen scientist Rob Stammes just heard a pin drop on Earth’s magnetic field.
“It was very quiet when it happened,” says Stammes, who runs a space weather observatory in Lofoten, Norway. On Oct. 17th, his magnetometer was monitoring Earth’s magnetic field as it does every night, and the instrument’s needle had settled itself into a straight line, indicating very low geomagnetic activity. Suddenly, Earth’s magnetic field began to ring.
“A very stable ~25 second magnetic oscillation appeared in my recordings, and lasted for more than 20 minutes,” he says. “It was fantastic to see the magnetic field swing back and forth by about 0.1 degrees, peak to peak.”
This kind of pure tone is rare, but it has happened before. Researchers call it a “pulsation continuous” — or “Pc” for short. Pc waves are classified into 5 types depending on their period. The waves Stammes caught fall into category Pc3.
The “pin dropping” was a gentle gust of solar wind. Imagine blowing across a piece of paper, making it flutter with your breath. The solar wind can have a similar effect Earth’s magnetic field. Pc3 waves are essentially flutters propagating down the flanks of our planet’s magnetosphere excited by the breath of the sun.
A NASA animation of waves fluttering down the sides of Earth’s magnetosphere [more]
Stammes is a longtime observer of Pc waves. Usually he catches them during Solar Minimum when “the room is quiet” for months at a time. “Recording one now so close to Solar Max is unexpected,” he says. “Lately, my magnetometer traces have been too noisy for such delicate waves–so it came a surprise!”
Pc3 waves, which can only be heard in moments of quiet, can also bring the quiet to an end. The oscillations sometimes flow all the way around Earth’s magnetic field and cause a “tearing instability” in our planet’s magnetic tail. This, in turn, sets the stage for magnetic reconnection and geomagnetic storms.
That didn’t happen on Oct. 17th, though. The pin dropped, the magnetosphere rang, and quiet resumed. Stammes is already listening for more. Stay tuned!
Oct. 8, 2023 : (Spaceweather.com) For the second time this year, a cryovolcanic eruption on Comet 12P/Pons-Brooks has expelled a cloud of debris in the shape of the Millennium Falcon. It was weird enough the first it happened in July. Now, in October, scientists are confronted with the challenge of explaining how a comet can shapeshift itself into a Star Wars freighter twice:
This image was taken on Oct. 7, 2023, by Jose Manual Perez of the Comet Chasers, the same group that discovered the outburst two days earlier. The double horns of the Falcon look just like they did in July 2023.
Richard Miles of the British Astronomical Association thinks 12P may be one of 10 to 20 known comets with active ice volcanoes. “The two ‘horns’ may be caused by a peculiarly-shaped cryovolcanic vent with some sort of blockage causing material to be expelled with a weird flow pattern,” he speculates.
This is *not* just a funny-shaped comet tail, he stresses. Miles used a JPL ephemeris to compare the direction of the horns with the expected direction of the comet’s dust and ion tails. It was a complete mismatch.
“The difference between the July horns and its October ones is about 55-60° projected on the sky,” says Miles. “The mismatch between either of these directions and the ion tail direction and dust tail direction was almost the most it could be!
Amateur astronomer Lars Zielke of Tvis, Denmark, has been tracking the outburst every night. This animation shows the change in only 24 hours (Oct. 7-8):
“What a difference in size!” says Zielke. “I think there is a hint of a globular dust cloud expanding around the comet’s core, and it is easy to see the expansion of the ‘horns’ of the Falcon.”
Comet 12P could attract widespread interest next year–especially if it continues to explode. The comet is falling toward the sun for a close encounter in April 2024 when it is expected to become a naked-eye object at 4th or 5th magnitude. Talk about perfect timing. 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. After its latest outburst, the comet is shining as brightly as an 11th magnitude star, putting it within range of mid-sized backyard telescopes. Look for 12P in the constellation Hercules just across the border from the bright star Vega. [sky map]
Oct. 5, 2023: (Spaceweather.com) The sun is about to lose something important: Its magnetic poles.
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 were happening on Earth, there were 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 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 the peak of 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
“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 effect 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!
), the broad band indicating the uncertainty of the forecast. It has become clear in recent years that the original prediction was too low, which prompted NOAA to issue a new one. The magenta line (
) traces the new forecast, and takes into account recent high sunspot counts.
Spaceweather.com 
