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By Robert Lea
9 May 2023
It's believed that only 3% of all sunspots display reverse polarity as this one does.
A general view during the northern lights also known as aurora, colorful lights shift in the sky in Abisko in Northern Sweden, Sweden on March 25, 2023. (Image credit: Gul Meltem Temiz Sahin/Anadolu Agency via Getty Images)
An outburst from a law-breaking new sunspot could pummel Earth with charged particles and trigger strong geomagnetic storms, potentially causing spectacular light shows in skies over the planet during the coming days.
The geomagnetic storms will be the result of a massive coronal mass ejection(CME) hurled directly toward Earth by an explosion at a sunspot designated AR3296 that took place at 6:54 p.m. EDT (2254 GMT) on Sunday, May 7. Energetic particles from the outburst will arrive at Earth in the early hours of Wednesday (May 10). The same explosion that launched this CME also caused a medium-strength M1.5-class solar flare.
The violent solar activity from sunspot AR3296 is expected to impact Earth over Wednesday (May 10) and Thursday (May 11), and could cause auroras normally seen at high latitudes to extend much further south to mid-latitudes, possibly making them visible in U.S. states such as Oregon, Nebraska, and Virginia, SpaceWeather.com reported(opens in new tab) on May 9.
The sunspot that produced the storm is referred to as having reverse polarity, meaning it has the opposite magnetic field of other sunspots found on the same hemisphere of the sun. Only a tiny percentage of sunspots display this reverse polarity, making this sunspot incredibly rare in addition to more likely to explode as this one already has.
Solar flares are composed of energy, light and high-speed particles, meaning this aspect of the solar explosion struck Earth ahead of the plasma of the CME. The extreme ultraviolet radiation from the solar flare ionized the top of Earth's atmosphere, producing a radio blackout over the western U.S. and the Pacific Ocean.
According to SpaceWeather.com's Tony Phillips (opens in new tab), sunspot AR3296 is considered a law-breaker because it runs contrary to a rule called Hale's Law (opens in new tab). This law suggests that during the current 11-year solar cycle, Cycle 25, sunspots in the Northern Hemisphere should have polarities that are positively charged on the right and negatively charged on the left; AR3296 reverses this by being negatively charged on the right and positively charged on the left.
A magnetogram (a representation of the variations in strength of the sun's magnetic field) produced by NASA's Solar Dynamics Observatory on May 7. The reverse polarity sunspot AR3296 can be found as a small blue spot above the center of the sun's disk in the image. (Image credit: NASA/SDO)
Such reverse polarity sunspots are fairly uncommon; studies have found that only around 3% of these cool patches break Hale's Law. While they tend to be the same size as normal polarity sunspots and last for the same amount of time, reverse polarity sunspots are twice as likely to be the site of complex magnetic fields in which positive and negative poles are mixed.
This makes reverse polarity sunspots more likely to explode and create CME outbursts and solar flares just like AR3296 is currently doing. This rule-breaking sunspot is set to travel around the limb of the sun and away from Earth by the weekend, ending its bombardment of our planet.
The rogue sunspot flared again during the morning of Tuesday, May 9, with this being its fourth M-class, or medium-sized, flare in around just 36 hours. The intensity of these AR3296 flares is increasing and SpaceWeather reports that an X-class flare is possible from AR3296 before the weekend.
X-class flares are the strongest solar flare with ten times the energy of an M-class flare, which themselves are ten times as strong as C-class flares.
According to EarthSky.org(opens in new tab), the forecast for flares from AR3296 between Tuesday and Wednesday is a 99% chance for C-class flares, a 55% chance for M-class flares, and a 20% chance for X-class flares.
Editor's Note: If you snap an image of auroras this week and would like to share it with Space.com's readers, send your photo(s), comments, and your name and location to spacephotos@space.com.
See: https://www.space.com/sun-reverse-s...-48B3-8626-903FF9B2FCAD&utm_source=SmartBrief
The following is an excerpt from: A Systematic Study of Hale and Anti-Hale Sunspot Physical Parameters
by Jing Li
Department of Earth, Planetary and Space Sciences, University of California at Los Angeles,
Los Angeles, CA 90095-1567
jli@igpp.ucla.edu
Sunspots are classified as either “Hale” or “anti-Hale”, depending on whether their polarities align or anti-align with Hale’s hemispheric polarity rule. We find that the “anti-Hale” sunspots constitute a mere fraction (8.1 ± 0.4)% of all sunspots, and this fraction is the same in both hemispheres and cycles; “Hale” sunspots obey Joy’s law in both hemispheres and cycles but “anti-Hale” sunspots do not. Three equivalent forms of Joy’s law are derived; sin γ = (0.38 ± 0.05) sin φ; γ = (0.39 ± 0.06)φ; and γ = (23.80 ± 3.51)sinφ, where γ is the tilt angle and φ is the heliospheric latitude; (3) The average Hale sunspot tilt angle is γ = 5.49◦ ± 0.09; (4) The tilt angles, magnetic fluxes and pole separations of sunspots are interrelated, with larger fluxes correlated with larger pole separations and smaller tilt angles. The “anti-Hale” sunspots are also much weaker than “Hale” sunspots in those parameters, but they share similar magnetic flux distributions and average latitudes.
Sunspot groups are formed when magnetic flux tubes rise, likely from the tachocline between the convection and radiation zones (van Ballegooijen 1982). Precisely how they form and the details of their ascent are invisible to observers. However, patterns of sunspot surface activity offer clues to the inner work of the global solar magnetic field. Sunspots are observed to consist of pairs with opposite magnetic polarities. They are generally elongated in the east-west direction and the leading polarities generally lean closer to the equator than the trailing polarities. Hale et al. (1919) noted that most leading spots have opposite polarities in opposite hemispheres, and also that the sense of this hemispheric polarity pattern switches from cycle to cycle. This is known as Hale’s hemispheric polarity rule, or simply “Hale’s law”. Separately, A. H. Joy noticed, and Hale et al. (1919) reported, that sunspot axes increasingly tilt with latitude, a trend known as Joy’s law. In addition to Hale’s and Joy’s laws, Sp ̈orer’s law describes the steady decrease of sunspot latitude through the solar cycle, forming a “butterfly diagram” in a time vs. latitude plot. Discovered by Richard Carrington around 1861, and refined by Gustav Sp ̈orer, the sunspot butterfly diagram is interpreted as the product of the dynamo waves (Parker 1955b) or the poloidal field stretching by differential rotation (Babcock 1961).
Hale’s, Joy’s and Sp ̈orer’s laws indicate that the solar magnetic fields change globally in a cyclic pattern. A widely-held description of solar magnetic activity centers on the interplay between a global poloidal field and differential rotation (Parker 1955b; Babcock 1961; Choudhuri 2000). When the global field is dominantly a poloidal field, the Sun is in an activity minimum and few or no sunspots are visible. As the global poloidal field is stretched into a toroidal field by differential rotation (Schou et al. 1998), the field lines are stretched in both latitudinal and radial directions, ultimately, giving rise to concentrated magnetic flux tubes. These flux tubes ascend due to magnetic buoyancy and, through the suppression of convection and of radiative output, appear as sunspots (Parker 1955a). At this stage, the surface of the Sun is occupied by more and more sunspots first at high latitudes, gradually at mid- and low latitudes, as the solar activity enters a maximum phase. Near the equator, the leading polarities of sunspot pairs annihilate with their counterparts on the opposite hemisphere. At the same time, the trailing polarities disintegrate and are transported to high latitudes by poleward meridional flows (Hathaway & Rightmire 2010). This dissipation process eventually results in a reversal of the polar fields at the height of solar activity maximum. The global field gradually evolves back to an axisymmetric dipole in the second part of the solar cycle (van Ballegooijen et al. 1998; Jiang et al. 2014) until the Sun enters the next activity minimum, with a polar fields opposite in sign to the previous minimum. As the new cycle starts, emerging sunspots have polarities opposite from the previous cycle, so accounting for Hale’s law.
The Coriolis force, acting on the rapid expanding flux ropes as they ascend through the con- vective zone, is probably responsible for the sunspot tilt (D’Silva & Choudhuri 1993; Howard 1994). If the magnetic flux is sufficiently strong in the overshooting region, the flux loop rises while having little interaction with the materials in the convection zone (van Ballegooijen 1982; Fan 2009). The sunspot tilt angle is determined by the Coriolis acceleration, −2ω(φ)sinφ(∆s/∆t), where ω(φ) is the sun’s spin rate at latitude φ and ∆s/∆t is the average separation rate of magnetic footpoints. Assuming the acceleration is constant, the sunspot tilt angle can be approximated as: sin γ ∼ ω(φ)∆t sin φ, where ∆t is the average time for sunspot group emergence at the surface, and φ is the latitude (Wang & Sheeley 1991).
The tilts of the sunspot magnetic axes provide the poloidal components needed for the global field to revert to an axisymmetric dipole configuration. For example, the contribution of an individ- ual sunspot group to the solar axial dipole field may be expressed as Dss ∝ sΦ sin γ cos φ where s is the pole separation, Φ is the total flux, γ is the tilt angle, and φ is the latitude (Jiang et al. 2014). Surface flux transport simulations confirm the importance of the sunspot tilt angles in determining the polar field strength (Cameron et al. 2010; Jiang et al. 2015) but the disintegration and transport of magnetic fields to the poles are imperfectly understood (Parker 2009). The mean normalized tilt angles are anti-correlated with the strength of the cycle. A close connection between the tilt angle and the helicity was recently reported by Pevtsov et al. (2014) and helicity has emerged as an important sunspot parameter to assess coronal mass ejections.
See: https://arxiv.org/pdf/1809.08980.pdf
Sunspots are observed to consist of pairs with opposite magnetic polarities. They are generally elongated in the east-west direction and the leading polarities generally lean closer to the equator than the trailing polarities. Hale et al. (1919) noted that most leading spots have opposite polarities in opposite hemispheres, and also that the sense of this hemispheric polarity pattern switches from cycle to cycle. This is known as Hale’s hemispheric polarity rule, or simply “Hale’s law”. Separately, A. H. Joy noticed, and Hale et al. reported, that sunspot axes increasingly tilt with latitude, a trend known as Joy’s law. In addition to Hale’s and Joy’s laws, Spörer’s law describes the steady decrease of sunspot latitude through the solar cycle, forming a “butterfly diagram” in a time vs. latitude plot.
Hartmann352
9 May 2023
It's believed that only 3% of all sunspots display reverse polarity as this one does.
A general view during the northern lights also known as aurora, colorful lights shift in the sky in Abisko in Northern Sweden, Sweden on March 25, 2023. (Image credit: Gul Meltem Temiz Sahin/Anadolu Agency via Getty Images)
An outburst from a law-breaking new sunspot could pummel Earth with charged particles and trigger strong geomagnetic storms, potentially causing spectacular light shows in skies over the planet during the coming days.
The geomagnetic storms will be the result of a massive coronal mass ejection(CME) hurled directly toward Earth by an explosion at a sunspot designated AR3296 that took place at 6:54 p.m. EDT (2254 GMT) on Sunday, May 7. Energetic particles from the outburst will arrive at Earth in the early hours of Wednesday (May 10). The same explosion that launched this CME also caused a medium-strength M1.5-class solar flare.
The violent solar activity from sunspot AR3296 is expected to impact Earth over Wednesday (May 10) and Thursday (May 11), and could cause auroras normally seen at high latitudes to extend much further south to mid-latitudes, possibly making them visible in U.S. states such as Oregon, Nebraska, and Virginia, SpaceWeather.com reported(opens in new tab) on May 9.
The sunspot that produced the storm is referred to as having reverse polarity, meaning it has the opposite magnetic field of other sunspots found on the same hemisphere of the sun. Only a tiny percentage of sunspots display this reverse polarity, making this sunspot incredibly rare in addition to more likely to explode as this one already has.
Solar flares are composed of energy, light and high-speed particles, meaning this aspect of the solar explosion struck Earth ahead of the plasma of the CME. The extreme ultraviolet radiation from the solar flare ionized the top of Earth's atmosphere, producing a radio blackout over the western U.S. and the Pacific Ocean.
According to SpaceWeather.com's Tony Phillips (opens in new tab), sunspot AR3296 is considered a law-breaker because it runs contrary to a rule called Hale's Law (opens in new tab). This law suggests that during the current 11-year solar cycle, Cycle 25, sunspots in the Northern Hemisphere should have polarities that are positively charged on the right and negatively charged on the left; AR3296 reverses this by being negatively charged on the right and positively charged on the left.
A magnetogram (a representation of the variations in strength of the sun's magnetic field) produced by NASA's Solar Dynamics Observatory on May 7. The reverse polarity sunspot AR3296 can be found as a small blue spot above the center of the sun's disk in the image. (Image credit: NASA/SDO)
Such reverse polarity sunspots are fairly uncommon; studies have found that only around 3% of these cool patches break Hale's Law. While they tend to be the same size as normal polarity sunspots and last for the same amount of time, reverse polarity sunspots are twice as likely to be the site of complex magnetic fields in which positive and negative poles are mixed.
This makes reverse polarity sunspots more likely to explode and create CME outbursts and solar flares just like AR3296 is currently doing. This rule-breaking sunspot is set to travel around the limb of the sun and away from Earth by the weekend, ending its bombardment of our planet.
The rogue sunspot flared again during the morning of Tuesday, May 9, with this being its fourth M-class, or medium-sized, flare in around just 36 hours. The intensity of these AR3296 flares is increasing and SpaceWeather reports that an X-class flare is possible from AR3296 before the weekend.
X-class flares are the strongest solar flare with ten times the energy of an M-class flare, which themselves are ten times as strong as C-class flares.
According to EarthSky.org(opens in new tab), the forecast for flares from AR3296 between Tuesday and Wednesday is a 99% chance for C-class flares, a 55% chance for M-class flares, and a 20% chance for X-class flares.
Editor's Note: If you snap an image of auroras this week and would like to share it with Space.com's readers, send your photo(s), comments, and your name and location to spacephotos@space.com.
See: https://www.space.com/sun-reverse-s...-48B3-8626-903FF9B2FCAD&utm_source=SmartBrief
The following is an excerpt from: A Systematic Study of Hale and Anti-Hale Sunspot Physical Parameters
by Jing Li
Department of Earth, Planetary and Space Sciences, University of California at Los Angeles,
Los Angeles, CA 90095-1567
jli@igpp.ucla.edu
Sunspots are classified as either “Hale” or “anti-Hale”, depending on whether their polarities align or anti-align with Hale’s hemispheric polarity rule. We find that the “anti-Hale” sunspots constitute a mere fraction (8.1 ± 0.4)% of all sunspots, and this fraction is the same in both hemispheres and cycles; “Hale” sunspots obey Joy’s law in both hemispheres and cycles but “anti-Hale” sunspots do not. Three equivalent forms of Joy’s law are derived; sin γ = (0.38 ± 0.05) sin φ; γ = (0.39 ± 0.06)φ; and γ = (23.80 ± 3.51)sinφ, where γ is the tilt angle and φ is the heliospheric latitude; (3) The average Hale sunspot tilt angle is γ = 5.49◦ ± 0.09; (4) The tilt angles, magnetic fluxes and pole separations of sunspots are interrelated, with larger fluxes correlated with larger pole separations and smaller tilt angles. The “anti-Hale” sunspots are also much weaker than “Hale” sunspots in those parameters, but they share similar magnetic flux distributions and average latitudes.
Sunspot groups are formed when magnetic flux tubes rise, likely from the tachocline between the convection and radiation zones (van Ballegooijen 1982). Precisely how they form and the details of their ascent are invisible to observers. However, patterns of sunspot surface activity offer clues to the inner work of the global solar magnetic field. Sunspots are observed to consist of pairs with opposite magnetic polarities. They are generally elongated in the east-west direction and the leading polarities generally lean closer to the equator than the trailing polarities. Hale et al. (1919) noted that most leading spots have opposite polarities in opposite hemispheres, and also that the sense of this hemispheric polarity pattern switches from cycle to cycle. This is known as Hale’s hemispheric polarity rule, or simply “Hale’s law”. Separately, A. H. Joy noticed, and Hale et al. (1919) reported, that sunspot axes increasingly tilt with latitude, a trend known as Joy’s law. In addition to Hale’s and Joy’s laws, Sp ̈orer’s law describes the steady decrease of sunspot latitude through the solar cycle, forming a “butterfly diagram” in a time vs. latitude plot. Discovered by Richard Carrington around 1861, and refined by Gustav Sp ̈orer, the sunspot butterfly diagram is interpreted as the product of the dynamo waves (Parker 1955b) or the poloidal field stretching by differential rotation (Babcock 1961).
Hale’s, Joy’s and Sp ̈orer’s laws indicate that the solar magnetic fields change globally in a cyclic pattern. A widely-held description of solar magnetic activity centers on the interplay between a global poloidal field and differential rotation (Parker 1955b; Babcock 1961; Choudhuri 2000). When the global field is dominantly a poloidal field, the Sun is in an activity minimum and few or no sunspots are visible. As the global poloidal field is stretched into a toroidal field by differential rotation (Schou et al. 1998), the field lines are stretched in both latitudinal and radial directions, ultimately, giving rise to concentrated magnetic flux tubes. These flux tubes ascend due to magnetic buoyancy and, through the suppression of convection and of radiative output, appear as sunspots (Parker 1955a). At this stage, the surface of the Sun is occupied by more and more sunspots first at high latitudes, gradually at mid- and low latitudes, as the solar activity enters a maximum phase. Near the equator, the leading polarities of sunspot pairs annihilate with their counterparts on the opposite hemisphere. At the same time, the trailing polarities disintegrate and are transported to high latitudes by poleward meridional flows (Hathaway & Rightmire 2010). This dissipation process eventually results in a reversal of the polar fields at the height of solar activity maximum. The global field gradually evolves back to an axisymmetric dipole in the second part of the solar cycle (van Ballegooijen et al. 1998; Jiang et al. 2014) until the Sun enters the next activity minimum, with a polar fields opposite in sign to the previous minimum. As the new cycle starts, emerging sunspots have polarities opposite from the previous cycle, so accounting for Hale’s law.
The Coriolis force, acting on the rapid expanding flux ropes as they ascend through the con- vective zone, is probably responsible for the sunspot tilt (D’Silva & Choudhuri 1993; Howard 1994). If the magnetic flux is sufficiently strong in the overshooting region, the flux loop rises while having little interaction with the materials in the convection zone (van Ballegooijen 1982; Fan 2009). The sunspot tilt angle is determined by the Coriolis acceleration, −2ω(φ)sinφ(∆s/∆t), where ω(φ) is the sun’s spin rate at latitude φ and ∆s/∆t is the average separation rate of magnetic footpoints. Assuming the acceleration is constant, the sunspot tilt angle can be approximated as: sin γ ∼ ω(φ)∆t sin φ, where ∆t is the average time for sunspot group emergence at the surface, and φ is the latitude (Wang & Sheeley 1991).
The tilts of the sunspot magnetic axes provide the poloidal components needed for the global field to revert to an axisymmetric dipole configuration. For example, the contribution of an individ- ual sunspot group to the solar axial dipole field may be expressed as Dss ∝ sΦ sin γ cos φ where s is the pole separation, Φ is the total flux, γ is the tilt angle, and φ is the latitude (Jiang et al. 2014). Surface flux transport simulations confirm the importance of the sunspot tilt angles in determining the polar field strength (Cameron et al. 2010; Jiang et al. 2015) but the disintegration and transport of magnetic fields to the poles are imperfectly understood (Parker 2009). The mean normalized tilt angles are anti-correlated with the strength of the cycle. A close connection between the tilt angle and the helicity was recently reported by Pevtsov et al. (2014) and helicity has emerged as an important sunspot parameter to assess coronal mass ejections.
See: https://arxiv.org/pdf/1809.08980.pdf
Sunspots are observed to consist of pairs with opposite magnetic polarities. They are generally elongated in the east-west direction and the leading polarities generally lean closer to the equator than the trailing polarities. Hale et al. (1919) noted that most leading spots have opposite polarities in opposite hemispheres, and also that the sense of this hemispheric polarity pattern switches from cycle to cycle. This is known as Hale’s hemispheric polarity rule, or simply “Hale’s law”. Separately, A. H. Joy noticed, and Hale et al. reported, that sunspot axes increasingly tilt with latitude, a trend known as Joy’s law. In addition to Hale’s and Joy’s laws, Spörer’s law describes the steady decrease of sunspot latitude through the solar cycle, forming a “butterfly diagram” in a time vs. latitude plot.
Hartmann352
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