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25 november 2025, 20:05 мск

The Earth has been in the zone of a solar coronal hole for the second day.

Geomagnetic index Kp
Geomagnetic index Kp

For the second day, the planet has been passing through a fast plasma stream formed in the coronal hole on the Sun, which unexpectedly reached Earth yesterday, two days earlier than predicted. The hole itself is clearly visible in solar images and has a very unusual, highly jagged shape, making it very difficult to understand what should be happening in interplanetary space and in what order. In fact, very high wind speeds, twice the normal level, are being recorded in the vicinity of Earth, combined with fairly normal plasma density and magnetic field induction. This was more than enough to upset the Earth's magnetic field, but not enough to cause anything more serious, which could have happened if the plasma stream had been at least three to four times denser. The Kp index graphs have noticeably yellowed over the past 24 hours, but the red level has only been breached once so far, and only weakly: a brief magnetic storm was observed in Moscow around midday today.

Geomagnetic activity, however, has had an unexpectedly strong impact on the intensity of the auroras. Over the past 24 hours, the auroral index has broken through the 10-point scale twice, but both times at particularly unfortunate times, especially today, when another surge occurred precisely mid-afternoon in the central part of the country. Overall, given the very high wind speeds observed, the Earth's magnetosphere should respond quite strongly to even small variations in plasma flow, and auroral surges will almost certainly continue. Unfortunately, clear skies are currently difficult to find across the country, but isolated images of auroras are still being received, primarily from the northern and northwestern regions.

The forecast for the duration of geomagnetic events is quite off due to their unexpectedly early onset, but the gap doesn't appear to be too large, and it's expected that the yellow-red band on the charts will begin to dissipate tomorrow morning, with the indices returning completely to the green zone by the end of the day. Flare activity is currently low—the star is still recovering from a series of X flares that occurred mid-month. Somewhere on the far side of the Sun, the legendary region 4274, which, in fact, raged there 10 days ago, is currently trying to survive until its return to Earth. Its return, if it occurs, is perhaps the main factor that could turn the space weather pattern upside down. The active centers currently observed on the Earth-facing side don't seem to be in any serious contention for now.

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Laboratory of Solar Astronomy,SRI RAS

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