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Comment by jjcm

18 days ago

If anyone is interested in what "G4" means in context, here's the scale: https://www.swpc.noaa.gov/noaa-scales-explanation

44 comments

jjcm

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Helmut10001  18 days ago

Interestingly, there are about 100 events of this severity (G4) per cycle, and a single cycle lasts 11 years. This means there are about nine G4 events on average per year.

  • tomr_stargazer  18 days ago

    Note, however, that the solar cycle [0] is so named due to its minimum and maximum: the most severe events will be clustered around the maximum, rather than spread out over the whole cycle (as your comment suggested) - so the "nine G4 events on average per year" is mathematically true but not so helpful.

    [0]: https://en.wikipedia.org/wiki/Solar_cycle

8bitsrule  18 days ago

G4: " Induced pipeline currents affect preventive measures, HF radio propagation sporadic..."

G5: " Pipeline currents can reach hundreds of amps, HF (high frequency) radio propagation may be impossible in many areas for one to two days..."

9dev  18 days ago

The scale seems capped at a pretty low upper end? It feels like with all the mindbogglingly huge numbers usually involved when talking about space, there must be much, much worse events possible. Is it just that we don't know enough about them due to lack of experience that these aren't included?

irthomasthomas  18 days ago

We are at kp 8.67. The Carrington event was a kp 9

  • keepamovin  18 days ago

    This is also related to weaker solar events leading to stronger Earth storms due to Earth's weakening magnetic field.

  • echelon  18 days ago

    Have we been having these more recently?

    I don't ever recall seeing these in the news so frequently. It feels like there are several a year now. A decade ago, never.

    And I also never remember seeing Aurora at my latitudes.

    Do we just have better sensing now, or is there some cycle on a period longer than a few years? Or maybe I'm crazy and just never noticed.

    • 0manrho  18 days ago

      Mid to late 2025 was the peak of an 11 year solar cycle (25th one since we've started keeping track). We're on the trailing end of that peak activity now, which is why the past year/several months has seemed so active compared to recent years past, and should decrease significantly (in frequency and intensity) as 2026 progresses.

      There was also a fairly significant geomagnetic storm back in November of 2025 as well.

      You can see the data here at NOAA's Space Weather site https://www.swpc.noaa.gov/products/solar-cycle-progression

    • ErroneousBosh  18 days ago

      > Have we been having these more recently?

      Yes, for suitable values of "recently".

      > And I also never remember seeing Aurora at my latitudes.

      How old are you?

      If you're younger than say your mid-40s you probably won't remember the early 80s, which is the last time we had a solar maximum that really came to anything.

      Solar activity rises and falls on an 11-year cycle, and right now we're experiencing quite a peak. The previous three, peaking in 2014, 2011, and 1989 were a bit of a bust.

      There was a massive peak in 1979 and I can remember my dad showing me the aurora when I was about six or seven - it seemed to be present most nights over the winter. That was also around the time of the CB Radio craze, where atmospheric conditions were such that you could use "skip" - bouncing radio signals off the highly-charged ionosphere - to talk to people hundreds of miles away as if they were just down the road, even on the comparatively high frequencies that CB used. There was a bit of a peak in the late 80s, and some good RF propagation too, as well as some incredible aurora - although the big one I remember was in about the end of 1991, early 1992.

      We had absolutely blistering hot summers followed by really cold and snowy winters, too, kind of like we're having at the moment.

      If the solar cycles have a longer repeating cycle of intensity on the scale of a hundred years or so (and it looks a bit like they do) then the next solar maximum in about 2036 is going to be even bigger.

non-  18 days ago

> Biological: Unavoidable radiation hazard to astronauts on EVA; passengers and crew in high-flying aircraft at high latitudes may be exposed to radiation risk.

Anyone have a sense of magnitude for this advisory? How much more radiation should an airline passenger expect to receive during a G4 event than normal?