On the evening of January 18, 2026, the sun unleashed a powerful X1.9 solar flare. This intense burst of energy launched a fast burst of solar material and magnetic fields – a coronal mass ejection (CME) – toward Earth. And when it reached our planet on the evening of January 19, it produced a rare G4 (severe) geomagnetic storm.
But while a severe storm holds the potential to trigger beautiful auroras at mid-latitudes, this storm’s real-world effects were surprisingly limited. Why? It was due to the storm’s magnetic makeup. The arrangement of the CME’s magnetic field limited how much energy actually reached Earth’s atmosphere, shaping which regions saw auroras and which did not.
EarthSky’s 2026 lunar calendar is available now. Get yours today! Makes a great gift.
Severe solar storm began with CME impact
The CME struck Earth’s magnetosphere at approximately 18:38 UTC on January 19, arriving with a sharp shock that immediately disturbed Earth’s magnetic field.
To understand what happened next, you need to know what Bz is. Bz describes whether the sun’s magnetic field is pointing north or south. This magnetic field is carried out into the solar system through the solar wind. And if the Bz is southward, it’s much easier for this solar wind to rush into Earth’s magnetosphere, or the magnetic bubble around our planet.
During the CME’s initial impact phase, the Bz briefly dipped strongly southward. So that allowed solar wind energy to flow efficiently into Earth’s magnetic field. This short-lived interaction quickly caused G4 (severe) geomagnetic storm levels, with Kp (another measure of Earth’s magnetic disturbance) exceeding 8.
Soon after the initial impact, the character of the severe geomagnetic storm changed dramatically. As Earth moved deeper into the core of the CME, the Bz – again, the orientation of the sun’s magnetic field – turned strongly northward.
This sustained northward orientation sharply limited the transfer of transfer into Earth’s magnetosphere. And that was what restricted the auroras, despite the overall strength of the storm.
This is why geomagnetic storm ratings can mislead
Conditions shifted southward again around 5:14 UTC on January 20, but the reversal was modest and short-lived. While this allowed for some renewed geomagnetic response, it was not sufficient to drive widespread auroras into mid or lower latitudes.
As a result, auroral activity remained largely confined to higher latitudes, even though the storm rating suggested a much wider impact. This severe solar storm clearly illustrates why Kp values and NOAA storm ratings alone do not fully describe auroral visibility or real-world effects.
Severe geomagnetic storm coincided with intense radiation event
Adding to the space weather complexity, the same X1.9 flare also triggered a solar radiation storm that reached S4 (severe) levels, making it the largest event in more than 20 years.
These storms occur when magnetic activity accelerates charged particles in the solar atmosphere to very high velocities. After making the journey to Earth in just tens of minutes, these then rain down at the poles. This can expose astronauts and those in high-latitude aircraft to increased radiation.
Not over yet
By the numbers, this was certainly a severe geomagnetic storm. But in practice, it was a selective and magnetically constrained event driven by an extremely strong CME. It is a reminder that space weather impacts depend on magnetic geometry, not just raw intensity.
This is what makes following space weather and chasing auroras both exciting and frustrating. Ultimately, it’s so rewarding when the sky finally delivers a spectacular show.
It should also be noted that the storm is not yet over – there could be more surprises tonight, January 20. Read our daily sun news for more information.
Bottom line: A powerful blast from the sun triggered a severe geomagnetic storm on the night of January 19, but the auroras weren’t as widespread as hoped. It’s because storm strength isn’t the only factor affecting auroras.
The post Severe geomagnetic storm! What happened to the auroras? first appeared on EarthSky.
from EarthSky https://ift.tt/YWvfSBG
On the evening of January 18, 2026, the sun unleashed a powerful X1.9 solar flare. This intense burst of energy launched a fast burst of solar material and magnetic fields – a coronal mass ejection (CME) – toward Earth. And when it reached our planet on the evening of January 19, it produced a rare G4 (severe) geomagnetic storm.
But while a severe storm holds the potential to trigger beautiful auroras at mid-latitudes, this storm’s real-world effects were surprisingly limited. Why? It was due to the storm’s magnetic makeup. The arrangement of the CME’s magnetic field limited how much energy actually reached Earth’s atmosphere, shaping which regions saw auroras and which did not.
EarthSky’s 2026 lunar calendar is available now. Get yours today! Makes a great gift.
Severe solar storm began with CME impact
The CME struck Earth’s magnetosphere at approximately 18:38 UTC on January 19, arriving with a sharp shock that immediately disturbed Earth’s magnetic field.
To understand what happened next, you need to know what Bz is. Bz describes whether the sun’s magnetic field is pointing north or south. This magnetic field is carried out into the solar system through the solar wind. And if the Bz is southward, it’s much easier for this solar wind to rush into Earth’s magnetosphere, or the magnetic bubble around our planet.
During the CME’s initial impact phase, the Bz briefly dipped strongly southward. So that allowed solar wind energy to flow efficiently into Earth’s magnetic field. This short-lived interaction quickly caused G4 (severe) geomagnetic storm levels, with Kp (another measure of Earth’s magnetic disturbance) exceeding 8.
Soon after the initial impact, the character of the severe geomagnetic storm changed dramatically. As Earth moved deeper into the core of the CME, the Bz – again, the orientation of the sun’s magnetic field – turned strongly northward.
This sustained northward orientation sharply limited the transfer of transfer into Earth’s magnetosphere. And that was what restricted the auroras, despite the overall strength of the storm.
This is why geomagnetic storm ratings can mislead
Conditions shifted southward again around 5:14 UTC on January 20, but the reversal was modest and short-lived. While this allowed for some renewed geomagnetic response, it was not sufficient to drive widespread auroras into mid or lower latitudes.
As a result, auroral activity remained largely confined to higher latitudes, even though the storm rating suggested a much wider impact. This severe solar storm clearly illustrates why Kp values and NOAA storm ratings alone do not fully describe auroral visibility or real-world effects.
Severe geomagnetic storm coincided with intense radiation event
Adding to the space weather complexity, the same X1.9 flare also triggered a solar radiation storm that reached S4 (severe) levels, making it the largest event in more than 20 years.
These storms occur when magnetic activity accelerates charged particles in the solar atmosphere to very high velocities. After making the journey to Earth in just tens of minutes, these then rain down at the poles. This can expose astronauts and those in high-latitude aircraft to increased radiation.
Not over yet
By the numbers, this was certainly a severe geomagnetic storm. But in practice, it was a selective and magnetically constrained event driven by an extremely strong CME. It is a reminder that space weather impacts depend on magnetic geometry, not just raw intensity.
This is what makes following space weather and chasing auroras both exciting and frustrating. Ultimately, it’s so rewarding when the sky finally delivers a spectacular show.
It should also be noted that the storm is not yet over – there could be more surprises tonight, January 20. Read our daily sun news for more information.
Bottom line: A powerful blast from the sun triggered a severe geomagnetic storm on the night of January 19, but the auroras weren’t as widespread as hoped. It’s because storm strength isn’t the only factor affecting auroras.
The post Severe geomagnetic storm! What happened to the auroras? first appeared on EarthSky.
from EarthSky https://ift.tt/YWvfSBG
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