M8.2 solar flare, Strong G4 geomagnetic storm watch
52 comments
·June 1, 2025Animats
idatum
> Times are "Eastern Prevailing Time", which is Eastern Daylight Time right now.
I'm trying to recall when I last ever saw "Eastern Prevailing Time" used.
Can anyone share why it's used?
I see more use of ET over that (for Eastern US) or better yet UTC/GMT.
op00to
It removes ambiguity between ET (which do I mean?), EST (oops I meant EDT), and EDT (oops I meant EST).
I suspect they probably had an issue related to this, and prevailing time seems to work for them.
UTC is probably better, but a little less intuitive for most people.
xhrpost
> So now, DC current in some key AC lines is monitored continuously...
Can power lines have multiple currents in them at once? What would that mean for when the AC phase is moving opposite the DC direction?
andy99
AC is a sinusoid at 60/50 Hz. In principle, adding a DC current is just an offset, so e.g. if you had 1 Amp of AC current it would look like a sine wave 1 Amp high (actually sqrt(2)=1.414 high using the usual convention but that's not important) and the wave would be centered at 0A so go from -1(.414) to 1(.414). If you had a DC current of -1A on top of that, it would just be offset by that amount, so would look like a sine wave with a minimum of -2.414 and a maximum of .414.
Tldr, DC is just like an offset to the voltage or current waveform which is itself a sine wave.
globular-toast
Electrical conductors are basically reservoirs of electrons that can move around freely. Think of a body of water like the ocean. There is a lot of movement happening all at the same time: the tides, the waves, rip currents etc.
A wire is an essential one dimensional conductor; the electrons can move only backwards or forwards. Think of a narrow channel of water like a canal or river. A canal has no current, while a river has a direct current: it always flows one way. But a tidal inlet has an alternating current. The net flow of water is zero, but there is still a constant movement of water, backwards and forwards.
At a tidal estuary both things are happening: there's a DC component caused by net egress of water and an AC component caused by the tide.
The analogy doesn't really work because bodies of water also have capacitance. Wires are more like pipes. But hopefully you get the idea. Another way to think of it is like shouting in the wind, if you know how sound works.
Look into Fourier transforms if you're interested in learning more.
zrm
> https://pjm.adobeconnect.com/p63ultsdb2v/
Apparently my browser does not support some content in the file I'm trying to view and I'm instructed to use, among other things, "Firefox undefined or later". Which may or may not be what I was trying to use to begin with.
Though it seems to work anyway, so okay then.
zoky
> "Firefox undefined or later"
Honestly, you should really upgrade to at least Firefox Null for the security updates, or even Firefox NaN if you’re okay with being on the bleeding edge.
Animats
That PJM training material uses some ancient Adobe product. Works fine, though.
qwertox
M8.2 is in the upper medium range (M = M1.0 to M9.9). Next comes X1 which is 10 times stronger than M10. M2 is 10 times stronger than M1.
We might see several of these per year during a solar maximum. So maybe we get some nice auroras.
Edit, TIL: Though the G4 is a different issue, which classifies the impact of a solar flare on our earth. These range from G1 (minor) to G5 (extreme). This means that it can disrupt radio communications and GPS, put stress on power grids and, interestingly, increase satellite drag. G4 storms are rare events and occur only a few times per 11-year solar cycle.
nozzlegear
> G4 storms are rare events and occur only a few times per 11-year solar cycle.
Did you mean G5 storms? If I'm reading NOAA correctly, we get about 100 G4 storms per cycle, but only 4 G5 storms per cycle.
dylan604
> interestingly, increase satellite drag.
was reading something about this last week. originally, I assumed that the satellite electronics were getting whacked, but that wasn't the actual reason. these storms can heat the atmosphere causing it to expand/swell during the heating which causes extra drag requiring faster than anticipated use of fuel for station keeping.
just another one of those issues of just how everything in the universe "works together" in the most interesting ways.
perihelions
A while back an entire Starlink launch was lost due to this atmospheric inflation,
https://news.ycombinator.com/item?id=30267587 ("Starlink lost 40 satellites to a geomagnetic storm (spacex.com)", 495 comments)
OskarS
I've read there was a huge solar flare in the 19th century that knocked out telegraph equipment all over the world. Do we know how strong that event was on that scale?
sva_
You're probably referring to the Carrington Event
https://en.m.wikipedia.org/wiki/Carrington_Event
The instruments to measure the strength of solar flares didn't exist, but I think it's estimated between X40 to X50.
For comparison, last may the strongest flare was X8.7
mobbin
I know absolutely nothing about solar weather beyond aurora visuals being a possible outcome depending on where you live. I missed the last chance to see at my latitude (rare) and don't want to miss again.
What could I subscribe to so as to be notified when such events happen?
mikeocool
The Aurora app on iOS can set to send a critical notification when you’re likely to see it in your location.
It alerted me (in New York) this morning at about 4AM — though I slept through it.
pyrophoenix
It means between an hour and 9 hours from now, we might have a Aurora down to Berlin level at 100%. Now the weather is not the best. More information in 2 hours.
BenjiWiebe
Note that this was published yesterday. The geomagnetic storm is underway right now.
lucasban
I’ve been using the “My Aurora Forecast & Alerts” app, which is pretty good. I’m using the pro version, but I think the main difference was removing some ads.
olddustytrail
For the UK there's https://t.me/aurorawatchuk on Telegram but I guess solar weather is globally applicable.
yread
You can kinda follow news about it on
https://community.spaceweatherlive.com/topic/3947-ar14100-m8...
Although it often sounds like people throwing fancy words around just to sound smart. And their predictions mostly dont work out
petee
NOAA Experimental Aurora Viewline prediction for tonight/tomorrow night -- https://www.swpc.noaa.gov/products/aurora-viewline-tonight-a...
cogogo
On October 10th 2024 there was an x1.8 event and it was basically right at us. First time I’d seen the aurora - happened to be on cape cod at the time where the light pollution isn’t so bad. Was pretty amazing with the naked eye but absolutely incredible in long exposure photos.
sva_
> CME Passage Continues; G3-G4 Still Possible Tonight, June 1st
https://www.swpc.noaa.gov/news/cme-passage-continues-g3-g4-s...
null
NooneAtAll3
if I read all the websites correctly... it has already ended??
---
NOAA map (https://www.swpc.noaa.gov/products/aurora-30-minute-forecast) shows huge auroras were at ~7-9 UTC and now are gone
https://solarham.com/ says "arrived faster than expected" and "threshold was reached at 08:00 UTC"
and the website linked, the https://www.spaceweatherlive.com/en/.html says "14:00 UTC - Geomagnetic activity Severe G4 geomagnetic storm (Kp8)" followed by "17:30 UTC - Geomagnetic activity Minor G1 geomagnetic storm"
sva_
NOAA: "CME Passage Continues; G3-G4 Still Possible Tonight, June 1st"
https://www.swpc.noaa.gov/news/cme-passage-continues-g3-g4-s...
hinkley
My brain tried twice to turn this title into the name of a new nvram device.
a012
M8.2 is also a very old model of Leica M
transcriptase
Hams: How’s the RF propagation with this one?
geerlingguy
My favorite site for tracking the metrics is https://solarham.com/
geoffeg
https://solar.w5mmw.net/ is also nice for a quick overview.
AStonesThrow
NOAA's gotchu covered!
curtisszmania
[dead]
PJM issued a geomagnetic disturbance warning, then an action. No emergency actions, and it's already over.
Times are "Eastern Prevailing Time", which is Eastern Daylight Time right now.Background:
These messages are from the US east coast power grid control room in Valley Forge, PA sending to people at generating stations and other key control centers. This is a slow-moving event. If the grid was stressed, there would be "Pre-Emergency Load Reduction" and "Conservative Operation" actions ordered. If there was real trouble, there would be many more actions. But things never got beyond preparing for trouble.
A geomagnetic disturbance event in 1989 caused transformer damage leading to outages. The solar flux going between power lines and conductive ground induces DC currents into the ground and lines, so that ground potential is different at different points. This causes partial saturation of transformers, and heating. That wasn't noticed until it was too late. So now, DC current in some key AC lines is monitored continuously, so power levels can be reduced if necessary.
Training materials for understanding this:[1] Start at slide 21.
Background info on how a power grid works.[2] Start with "PJM 101"
[1] https://pjm.adobeconnect.com/p63ultsdb2v/
[2] https://www.pjm.com/training/training-resources