hckrnws

A big open question appears to be "how often do storms of this magnitude occur"

If we wanted answers to that, I think we could inspect chunks of iron containing mudstone deposited anytime in the past few million years. By looking at the magnetic alignment of iron particulates, you will learn the magnetic field when the particle was laid down. With particles being so small, it seems likely one could reconstruct 5 minutely magnetic field angle, albeit with a big linearity error on the time axis due to the uncertainty in rate of silt deposits.

However, such a measurement should still give a good estimate of the frequency and magnitude of geomagnetic storms.

They look for carbon 14 isotope spikes in ancient tree rings, and compare to beryllium 10 and chlorine 36 in ice cores

We've developed a fairly decent record of events back to 14,000 years ago

Look up 'Miyake events'

https://en.wikipedia.org/wiki/Miyake_event

This keeps getting more interesting!

> Six diverse historical occurrences, from archaeological sites to natural disasters, have thus been dated to a specific year, using Miyake events as benchmarks and counting tree rings. For example, wooden houses in the Viking site at L'Anse aux Meadows in Newfoundland were dated by finding the 993 CE Miyake event and then counting tree rings, which showed that the wood is from a tree felled in 1021 CE.[

13000 years ago seems like a special moment for a few events. Is it possible that say a volcano eruption, or a meteor strike saturates the atmosphere and normal cosmic ray interaction with soot and so on can attribute to what they detect in trees?

According to Wikipedia:

> At present, five significant events are known (7176 BCE, 5259 BCE, 660 BCE, 774 CE, 993 CE)

Seems like the Carrington event wasn't strong enough to be considered a Miyake event.

Interesting one is 12k years ago around Younger Dryas

Are you suggesting this because you have some knowledge of the field and are aware that this work hasn't been done? It seems like if it were so simple someone might have taken a look. Magnetic analyses of rock deposits are after all how we know about things like the timing and frequency of magnetic pole flips.

The Carrington event lasted about 2 weeks. How much silt is deposited in that time?

I suspect it hasn't been done because there was no obvious value to such data, and the effort of figuring out the precise position and magnetic orientation of trillions of iron particles would be pretty high...

Lloyd’s of London is a large insurer and is very interested in the potential liability that they are exposed to from the various insurance policies that they’ve underwritten.

In 2013, they published a report[0] considering the effects of solar storm risk to the North American electric grid.

tldr; it’s all about the transformers

[0] - https://assets.lloyds.com/assets/pdf-solar-storm-risk-to-the...

> I think we could inspect chunks of iron containing mudstone deposited anytime in the past few million years. By looking at the magnetic alignment of iron particulates, you will learn the magnetic field when the particle was laid down.

This method has been used to identify the reversal of the magnetic pole. [1]

Generally tho, such solar storm lasts for way too short amount of time to leave permanent evidence in the rock layers. However, I believe they have studied deviations in tree trunk rings.

1: https://en.wikipedia.org/wiki/Geomagnetic_reversal

And to prove the theory of continential drift (through Paleomagnetism [0]). Shame that Wegener [1] didn't live to see his theory vindicated.

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

[1] https://en.wikipedia.org/wiki/Alfred_Wegener

I found the software they used for digitization to be interesting: https://markummitchell.github.io/engauge-digitizer/

Something similar which is more recently-maintained: https://github.com/automeris-io/WebPlotDigitizer

If they had used polygonal mirrors instead of flat ones they would not have lost any data.

Given the topic, is it possible for a solar flare to happen that is so large that aurora reach sea level? Or does it turn to Cherenkov light at that point?

Given the energy range of protons from the sun, it seems that the only way they can reach sea level is if much of the atmosphere were already swept away by some huge event.

I'm amazed that the scientific community of the time happened to have some kind of equipment to measure this phenomenon... all right before the time of the American Civil War.

London had an earlier version of the Underground while we were busy burning things and shooting at each other in the swamps…

happened to have some kind of equipment

Maxwell's A Dynamical Theory of the Electromagnetic Field was published in 1865 - it's mostly your perception of the history of the relevant science that might be a few decades off.

Why so snarky? The paper you refer to was published after the event. I'm also amazed that it was possible to record such event at that time.

I'm not sure where you got snarky, I'm just giving a little info on the state of scientific development of that particular field at the time. You need plenty of previous work to get to a theory of electromagnetism, as Maxwell did. If you prefer something a little earlier and more experimental Faraday published his seminal result in 1831. It took him about 10 years of fiddling with wires and magnets.

I'm also amazed

Which is wonderful! So were 19th century scientists, though, and they also figured it out.

The comment you are responding to, does not seem at all snarky to me. Just sayin'.

They didn’t just happened to have experiments set up to measure the magnetic field, improving navigation is really important if your power comes from trade so this sort of thing is funded.

And yet they were saving money by reusing photographic plates, bacause (as the article said) the observatory was constantly in danger of running out of funding. I guess science has always been underfunded.

[flagged]

copy editors and proof readers are the people trained to catch those types of errors but are seen more and more as an unnecessary expense.

peer reviewers assess scientific interest and quality.

edit: also, the abstract was almost certainly written after peer review.

That was the geomagnetic storm they didn’t want you to know about.