'Cataclysmic' solar storm hit Earth around 2687 years ago, ancient tree rings reveal

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If this colossal solar storm hit our technologically advanced world the effects would have been devastating.

solar storm erupting from the surface of the sun in a large fiery filament.
If this colossal solar storm hit our technologically advanced world the effects would have been devastating. (Image credit: Science Photo Library via Getty Images)

Earth is no stranger to solar storms. Just this year we've been bombarded with storms, some so powerful they've triggered jaw-dropping auroras deep into mid-latitudes.

Modern technology ensures that very little goes unnoticed. A fleet of satellites constantly monitors space weather, while scientists analyze data and study its effects on Earth. Meanwhile, skywatchers turn their gaze and cameras skyward to capture the mesmerizing auroras ignited by geomagnetic storms. But what about solar storms that took place prior to the creation of modern technology? If a solar storm of unprecedented magnitude occurred thousands of years ago how would we know?

Lucky for us ancient trees act as time capsules, silently recording Earth's history. A research team from the University of Arizona led by Irina Panyushkina and Timothy Jull is unlocking these arboreal secrets by carefully analyzing tree rings to reveal evidence of colossal solar storms known as Miyake Events. These space weather events are so rare that only 6 have been detected in the past 14,500 years. The most recent of which occurred around 775-775 CE. But the exact timing of the ca. 660 BCE event had long eluded researchers, until now.

Miyake events represent an extreme type of solar activity first identified in 2012 by Japanese physicist Fusa Miyake.

"If they happened today, they would have cataclysmic effects on communication technology," Panyushkina said in a statement.

Miyake, a collaborator with Panyushkina's team, published research revealing the distinctive signature of these events: sharp increases in radioactive carbon isotopes, specifically carbon-14, found in tree growth rings, according to the statement.

Carbon-14 is a naturally occurring radioactive variant of carbon, it forms in the atmosphere when cosmic radiation interacts with nitrogen. Eventually, this carbon-14 reacts with oxygen to form carbon dioxide. The carbon dioxide then enters the trees via photosynthesis.

"After a few months, carbon-14 will have traveled from the stratosphere to the lower atmosphere, where it is taken up by trees and becomes part of the wood as they grow," Panyushkina said in the statement.

fallen ancient trees cover a muddy river bank there is a red shovel standing in the sediment.

The trunk of an ancient larch tree lies exposed on the muddy banks of the river Ob in Siberia. Samples from such trees that lived a long time ago allowed the researchers to search for spikes in radiocarbon documenting extreme solar storms in the distant past. (Image credit: Irina Panyushkina)
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Panyushkina and her team at the University of Arizona carefully dissected individual tree rings from ancient wood samples collected from dead trees buried in riverbanks as well as timbers excavated during archaeological digs. The main component of the wood, the cellulose, is then burned to determine the radiocarbon content.

When a radiocarbon spike is detected, the researchers then compare the tree-ring data to spikes in different isotopes such as beryllium-10 which has been locked away in ice cores retrieved from glaciers and ice sheets, another great natural time capsule. Just like carbon-14, beryllium-10 forms in the atmosphere as a result of a bombardment of solar particles, precipitation such as rain or snow captures the isotope and locks it into an ice sheet.

"If ice cores from both the North Pole and South Pole show a spike in the isotope beryllium-10 for a particular year corresponding to increased radiocarbon in tree-rings, we know there was a solar storm," Panyushkina said in the statement.

Both tree ring and ice data pinpointed the date of an extreme Miyake solar storm whose timing had long eluded researchers to between 664 and 663 BCE.

The study is published in the journal Communications Earth & Environment.

Editor's note: This article was updated on Dec. 2 to correct the date of the most recent Miyake event, which occurred around 775-775 CE.

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Daisy Dobrijevic
Daisy Dobrijevic
Reference Editor

Daisy Dobrijevic joined Space.com in February 2022 having previously worked for our sister publication All About Space magazine as a staff writer. Before joining us, Daisy completed an editorial internship with the BBC Sky at Night Magazine and worked at the National Space Centre in Leicester, U.K., where she enjoyed communicating space science to the public. In 2021, Daisy completed a PhD in plant physiology and also holds a Master's in Environmental Science, she is currently based in Nottingham, U.K. Daisy is passionate about all things space, with a penchant for solar activity and space weather. She has a strong interest in astrotourism and loves nothing more than a good northern lights chase! 

9 Comments Comment from the forums
  • m4n8tpr8b
    These space weather events are so rare that only 6 have been detected in the past 14,500 years, the most recent of which occurred just between 664 and 663 BCE.

    You copied a mistake from the UofA press release. However, as correctly told in the actual scientific paper, there have been two more recent events in 774–775 CE and 993–994 CE.
    Reply
  • Meteoric Marmot
    It would be useful to know if these events happened at the peak of the solar cycle, but I'm assuming there's no way to discern that so far into the past. Unless there's a low-amplitude background 11-year cycle imposed on the data from CMEs?
    Reply
  • m4n8tpr8b
    There is an 11,400-year reconstruction of sunspot numbers based on tree ring & radiocarbon data which doesn't resolve solar cycles but has 10-year bins. Below are the reconstructed mean sunspot numbers for the ten-year bins containing the five identified Miyake events within that period:

    7176 BCE: 21.1 +/-10.8
    5259 BCE: 7.1 +/- 8.0
    664–663 BCE: 5.6 +/-7.1
    774–775 CE: 8.9 +/-7.1
    993–994 CE: 14.9 +/-8.1

    Most of these values are for low mean sunspot activity. The mean number of recent cycles was multiples of even the mean for the ten-year bin containing the 7176 BCE event.
    Reply
  • fj.torres
    The sun is to all appearances a relative calm and stable star when compared to the majority of similar stars. Red dwarfs in particular are way more active.
    What for the sun look to be rare events like Carrington and Miyake storms look to be regular if not frequent on most studied stars. Worse is possible.

    Doesn't bode well for the SETI crowd.
    And that is before Exoplanet Size distribution and orbital mechanics are factored in.
    The case for rare Earth theory grows stronger almost daily.
    Reply
  • danR
    fj.torres said:
    The sun is to all appearances a relative calm and stable star when compared to the majority of similar stars. Red dwarfs in particular are way more active.
    What for the sun look to be rare events like Carrington and Miyake storms look to be regular if not frequent on most studied stars. Worse is possible.

    Doesn't bode well for the SETI crowd.
    And that is before Exoplanet Size distribution and orbital mechanics are factored in.
    The case for rare Earth theory grows stronger almost daily.
    The answer to the Fermi Paradox, rather than being a needle in a haystack, is turning into an embarrassment of riches:

    Asteroid strike
    AGW+willful ignorance
    Super-Carrington event
    Nuclear War
    Unregulated-LLM insanity
    Presumption of technological/social resilience
    Reply
  • fj.torres
    danR said:
    The answer to the Fermi Paradox, rather than being a needle in a haystack, is turning into an embarrassment of riches:

    Asteroid strike
    AGW+willful ignorance
    Super-Carrington event
    Nuclear War
    Unregulated-LLM insanity
    Presumption of technological/social resilience
    Some of the "great filters" assume a *technological* civilization was able to rise up to start with.

    A number of the emerging hurdles can prevent the emergence of anything but the most basic forms of life.

    Instead of throwing up made up, wishful thinking numbers into the drake equation, the proper first step is identifying a significant number of stable sun-sized stars. Then identify the system planets and see how many reside in the habitable zone, have an atmosphere, and what kind of an atmosphere.
    Then try to figure out how long that planet has been habitable.
    Because for most of its 4.54B years, Earth itself was not habitable by our standards. Multicellular organisms only go back 600M years.

    And then there is the matter of intelligence and its survival. The human lineage can be traced to a population bottleneck of a few hundred specimens. Entire lineages of hominids died out despite intelligence level comparable to homo sapiens sapiens. They didn't last long enough to develop any kind of civilization. And even today, there are pockets of humanity that never developed any but the most basic form of civilization.

    By every known measure, we are outliers on a barely habitable planet in an oddball planetary system around an unusual stable star. Most stars are binaries. Most stars are red dwarfs. Even the sun's neighborhood in the galaxy is unusual within a low density bubble created by supernova explosions.

    We don't know enough to be even pretending to know why we exist , much less wondering why we seem to be alone. Occams Razor suggests that absent indisputable evidence to the contrary, we appear to be alone because we are alone.

    As we work to learn more and more about our place in the universe and how we got here, the evidence piling up points to us being a low probability outcome, lucky to have survived even this far.

    And we're not done; it is just that now we can start worrying about surviving our own Great Filters.
    Reply
  • Torbjorn Larsson
    A Miyaki event produces an order of magnitude more C14 than the technology interrupting Carrington event (~ 10 % vs 1 % annual increase).

    m4n8tpr8b said:
    You copied a mistake from the UofA press release. However, as correctly told in the actual scientific paper, there have been two more recent events in 774–775 CE and 993–994 CE.
    The paper is hard to read but it lists six events and then refer to them as Miyake type events (and mentions several other smaller events).

    Since that time, there have been numerous studies confirming these two events 6,7,8,9] as well as identifying additional events at ca. 660 BCE10, 5259 BCE, 7176 BCE11 and 12,450 BCE12. Six of these events are clearly tied to solar cosmic-ray events, as 10Be has been independently measured at these times in ice cores13,14,15, and they have been termed “Miyake Events” (ME). Other smaller events not clearly tied to solar proton events (as they are not confirmed independently by 10Be content in ice cores) have also been reported.
    Reply
  • Torbjorn Larsson
    fj.torres said:
    The case for rare Earth theory grows stronger almost daily.
    The "rare Earth" filters are daft since they are untestable. just add more factors until you get the answer you want to have. Almost as dumb as calling the opposite to Fermi's answer to "where are they" his "paradox". Fermi noted that we don't know if interstellar travel is possible, until we do there is no paradox.

    The evolution process that split biology from geology was easy, both rapid and strongly diversifying. The ~ 4.3 billion year old half alive first cells were already at ~ 4.2 billion years ago an advanced DNA LUCA that lived in an ecology of other cell populations and viruses. et al. The physiology and habitat of the last universal common ancestor. Nat Microbiol 1, 16116 (2016). Moody, E.R.R., Álvarez-Carretero, S., Mahendrarajah, T.A. et al. The nature of the last universal common ancestor and its impact on the early Earth system. Nat Ecol Evol 8, 1654–1666 (2024).]
    Here we infer that LUCA lived ~4.2 Ga (4.09–4.33 Ga) through divergence time analysis of pre-LUCA gene duplicates, calibrated using microbial fossils and isotope records under a new cross-bracing implementation. Phylogenetic reconciliation suggests that LUCA had a genome of at least 2.5 Mb (2.49–2.99 Mb), encoding around 2,600 proteins, comparable to modern prokaryotes. Our results suggest LUCA was a prokaryote-grade anaerobic acetogen that possessed an early immune system. Although LUCA is sometimes perceived as living in isolation, we infer LUCA to have been part of an established ecological system.
    So life cannot be rare, if the universe is habitable.

    That Earth is likely alone or at best with very rare analogs is likely not due to "filters" but because evolution of specific traits, such as language capable species, in a combinatorially diversifying branch process happens once in a blue moon.
    Reply
  • fj.torres
    Torbjorn Larsson said:
    The "rare Earth" filters are daft since they are untestable. just add more factors until you get the answer you want to have. Almost as dumb as calling the opposite to Fermi's answer to "where are they" his "paradox". Fermi noted that we don't know if interstellar travel is possible, until we do there is no paradox.

    The evolution process that split biology from geology was easy, both rapid and strongly diversifying. The ~ 4.3 billion year old half alive first cells were already at ~ 4.2 billion years ago an advanced DNA LUCA that lived in an ecology of other cell populations and viruses. et al. The physiology and habitat of the last universal common ancestor. Nat Microbiol 1, 16116 (2016). Moody, E.R.R., Álvarez-Carretero, S., Mahendrarajah, T.A. et al. The nature of the last universal common ancestor and its impact on the early Earth system. Nat Ecol Evol 8, 1654–1666 (2024).]
    So life cannot be rare, if the universe is habitable.

    That Earth is likely alone or at best with very rare analogs is likely not due to "filters" but because evolution of specific traits, such as language capable species, in a combinatorially diversifying branch process happens once in a blue moon.
    I wasn't referring to the rare earth factors as filters.

    Just that the proponents of the Great Filters are pre supposing that technical civilizations are common enough for them to come into play. With no evidence to suggest any of the pre requisites are met.
    Reply