Zonnevlammen, Zonnestormen en CME #6:

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Earth’s electrical rings released rare energy leak during recent G2 geomagnetic storm

A G2 – Moderate geomagnetic storm on October 18, 2025, produced an extremely bright red SAR arc visible from the United States to northern Europe. The event showed an unusually efficient release of energy from Earth’s ring current system, challenging current understanding of how the planet’s magnetic field interacts with the atmosphere.

A deep red band of light stretched across the night sky on October 18, seen from Maine to Sweden and Finland. The phenomenon followed a moderate G2-class geomagnetic storm caused by a coronal mass ejection grazing Earth’s magnetosphere. While the storm’s strength was typical, the optical display was not.

“My son and I were surprised by this red bow in the south,” said P-M Hedén, who photographed the emission from Norrtälje, Sweden. “It was so bright, I could see its reflection in a local pond.” Observers in southern Öland, Sweden; Searsport, Maine; and southern Finland captured similar images, confirming that the arc extended across the Atlantic sector.

“Only a few times in a solar cycle do we get an SAR arc this bright,” said Jeff Baumgardner of Boston University’s Center for Space Physics, who has studied the phenomenon for decades. “It nearly saturated our detectors.” He estimated the arc was 10 to 30 times brighter than a G2 storm would normally produce, a figure still awaiting calibrated data.

SAR arcs, or Stable Auroral Red arcs, occur when thermal energy from Earth’s ring current leaks into the upper atmosphere. The ring current is a torus-shaped flow of charged particles encircling Earth between about three and eight Earth radii, carrying electrical currents of millions of amperes.

During geomagnetic storms, part of this energy escapes along magnetic field lines and heats dense plasma near the boundary of the plasmasphere. Excited atomic oxygen then emits red light at a wavelength of 630 nanometers, producing the characteristic glow.

SAR arcs were first identified in 1956, at the dawn of the Space Age. Early researchers mistook them for auroras and named them “Stable Auroral Red arcs,” a misnomer since they do not originate from charged particles streaming in from space but from heat conduction within the ring-current region.

The red emission is difficult for human eyes to see directly because night vision is relatively insensitive to red light. Nonetheless, the October 18 arc was bright enough to be visible to the naked eye at mid-latitudes, an uncommon occurrence for a storm of moderate intensity.

According to NOAA’s space-weather scale, a G2 storm represents a moderate disturbance, typically too weak to produce such bright emissions. The brightness and geographic reach, from North America across the Atlantic to northern Europe, suggest an unusually strong energy transfer between the ring current and the ionosphere.

Comparable large-scale SAR arcs have been documented only a few times in recent decades, notably during the October 29, 1991, geomagnetic storm and a global SAR event in November 2023. The 2025 occurrence joins this short list, distinguished by its brightness despite moderate storm strength.

Researchers at Boston University and collaborating institutions are compiling ground-based and satellite observations, including data from NOAA’s GOES spacecraft and ESA’s Swarm constellation, to determine why this event was so luminous.

For now, the October 18 SAR arc demonstrates that even moderate solar disturbances can produce complex and visually striking energy exchanges within Earth’s magnetic environment. The mechanism behind this unusually bright leak remains under investigation.

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Op dinsdag 4 november 2025 23:23 schreef Houtenbeen het volgende:
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Op woensdag 5 november 2025 01:06 schreef Adrie072 het volgende:

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Long duration X1.7 solar flare erupted from Sunspot 4274
A major long-duration solar flare measuring X1.7 erupted from Active Region 4274 at 07:35 UTC on November 9, 2025. The event started at 07:01 and ended at 07:55 UTC. The region is located at the center of the solar disk, making Earth-directed CMEs very likely.

A Type II Radio Emission, with an estimated velocity of 804 km/s, and a Type IV emission were associated with the event, indicating a strong coronal mass ejection (CME) was produced during the event.

Additionally, a 10cm Radio Burst lasting 25 minutes and with a peak flux of 25 minutes was detected from 07:10 to 07:35 UTC. A 10cm radio burst indicates that the electromagnetic burst associated with a solar flare at the 10cm wavelength was double or greater than the initial 10cm radio background.

This can indicate significant radio noise associated with a solar flare. This noise is generally short-lived but can cause interference for sensitive receivers, including radar, GPS, and satellite communications.

The region is directly facing Earth, making an Earth-directed CME from this event very likely. It has a ‘beta-gamma-delta’ magnetic configuration and is capable of producing more major eruptions on the Sun. Earth-directed CMEs from this region are possible in the days ahead.

Solar wind parameters in 24 hours to 00:30 UTC on November 9 reflected remnant CME effects and negative polarity coronal hole high speed stream (CH HSS) influences. Total field strength gradually decreased from 11 nT to 5 nT. Bz was sustained southward, by as much as -9 nT, between 0000-08:30 UTC on November 8. Solar wind speeds ranged from 575 to 700 km/s, while Phi was predominantly negative.

Solar wind parameters are expected to remain enhanced through November 11 with negative polarity CH HSS influences (November 9-11) and the anticipated arrival of a CME from November 7 (November 10-11).