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Preserving the chronological record of geomagnetic ‘solar storms’ that impact Earth’s biosphere, against the Sun’s future disturbances – a hardened record documenting observed solar activity, safeguarding this essential space climate knowledge to aid posterity in living with our ‘stormy star’.

Solar 1





On 1–2 September 1859, Earth experienced a ‘curious’ geo-atmospheric event. Vibrant auroras brazenly danced outwards from the planet’s polar regions, illuminating the night sky sufficiently for startled people and wildlife to confuse this encroaching light for the imminent dawn. These concerning auroras were observable even at lower latitudes in the equatorial tropics, showering energetic purples, reds, blues, and rich green hues across south-central Mexico, Cuba, Hawaii, Queensland, southern Japan, and China. The eerie radiance unnerved many who witnessed the strange glow, with some believing the light to be of supernatural origin, while others reportedly harnessed the unanticipated illumination to read their local newspapers at nightime. Telegraphs sizzled to dysfunctional life with an abhorrent spectrum of interference, sometimes electrocuting station operators who risked touching their equipment. Early telegraph services were also documented to operate without an attached battery power supply, while other circuits failed as the pylons uncontrollable sparked and burst into flames. Compass needles reportedly went haywire and spun frantically; becoming futile tools for locating magnetic North. These strange phenomena were reported worldwide, occurring across a fleeting window of mere days, before ceasing and fading into a mystery no sooner than they had abruptly appeared. This curious tale would later become known as the infamous ‘Carrington Event’.



The Sun supports all terrestrial life cycles, such as the circadian rhythm, and many geochemical cycles across the Earth’s dynamic biosphere. However, our local star also undergoes its own cyclic solar maximum period; a timeframe where fierce surface activity and emissions can erupt outwards into the encapsulating Solar System, influencing everything from the density of [and fluctuations in] the prevailing solar winds, to radically influencing the atmospheric conditions of worlds dozens of light-minutes away from the Sun’s own photosphere. Known alternatively as the Schwabe or sunspot cycle, each period lasts for an average length of 11 years (all recorded cycles fall between 9.0–13.6 years, but the length of a Solar Cycle is still contested, and no two cycles are alike). Presently, we are situated within Solar Cycle 25 which began around December 2019, with the first recorded Solar Cycle commencing around February 1755. Over the course of these

11-year cycles, levels of solar radiation and ejection of stellar material, the frequency and scale of sunspots, solar flares, and coronal loops all demonstrate patterns in fluctuation; proceeding from a period of minimum activity, to a period of a maximum activity, and then back again to minimum activity. This gradual transition demarcates the natural end and beginning for a ‘typical’ cycle. Essentially, we know our moody star becomes aggressive, and its behavioural cycles are predictable, but the extent of its outburst are unforeseeable.

Throughout the documented fluctuations within a standard Solar Cycle, the quantity [and decay] of sunspots releases prodigious amounts of magnetic flux across the Sun’s outer photosphere. This flux forms ‘loops’ of magnetic knots that violently oppose, twist, and contort around one another, comparable to twisting a sphere of rubber bands, wrapping up elastic tension energy with each unbearable twist. Like strained rubber, torsions of opposing polarity can eventually [and violently] ‘snap’; suddenly releasing the burden of magnetic energy held within the outer corona. The re-configuring of stresses from this process of ‘Magnetic Reconnection’ subsequently discharges intensive bursts of energy and clouds of magnetically-bound plasma outwards, before the breaking points – now free of their vexing magnetic troubles – reassert themselves to a lower, balanced energy state. These natural disturbances within the Sun’s magnetic field simply increase the amount of stellar material hurtling outwards from the corona; causing associated phenomena such as density fluctuations in the prevailing solar winds, Solar Flares (intense bursts of electromagnetic radiation, most often in non-visible frequencies), and sometimes Coronal Mass Ejections (an expulsion of massive volumes of magnetically-charged plasma) of varying intensities to erupt – re-distributions of stellar mass and energy with the potential to affect the entire Solar System, and beyond.


Observed occurrences of these ‘behavioural’ phenomena are simply known under the nonspecific blanket term of ‘geomagnetic storms’. Each type of stellar shower however, travels at different velocities, ensuring that an eruption will subsequently arrive at our planet in three distinctive stages. Firstly, high-energy sunlight, mostly x-rays and ultraviolet light, ionises Earth's upper atmosphere about 8 minutes after departing the Sun’s corona; powerful emissions that can interfere with orbital telecommunications equipment and navigation services that varyingly operate across select radio frequencies. Thereafter, a radiation storm washes over the Earth’s magnetosphere like a tidal wave; creating potentially dangerous living conditions for unprotected astronauts about 23 minutes to two hours after departing the Sun. As this secondary wave can increase the prospect of damage to DNA within living cells, early warning space probes help to furnish astronauts with sufficient time to seek refuge. For this very reason, the International Space Station has increased shielding around crew quarters, but space agencies are mandated to monitor each astronaut’s radiation exposure for safety.

Finally, but not always after a Solar Flare, a CME consisting of a slower moving cloud of charged particles (i.e. plasma), reaches Earth’s magnetosphere after several hours or days of slower transit across interplanetary space. This material can violently react with Earth’s magnetosphere in addition to inducing widespread electromagnetic interference across electrical systems, and compacting the daylight-facing geomagnetic field lines, while also stretching out the night-facing side of this protective cocoon into a long diametric ‘tail’ away from the Sun. If geomagnetic storms are compared with a conventional chemical explosion, solar flares may be described as the initial ‘flash of light’, the ensuing pressure and heat waves as the ‘radiation shower’, and finally the damaging shrapnel cloud as a CME aftershock which continues to bombard onlookers for some time after the detonation has occurred. Depending upon the intensity of a stellar eruption, this solar bombardment can stretch Earth’s magnetic tail to the point of snapping; an act that then drags some of this plasma back with it towards our planet’s pole regions – in the process, creating stunningly bright auroras and inducing global electromagnetic interference. Most flares and ensuing geomagnetic storms are of moderate energetic output (with a classification system established to measure intensities according to the peak flux of X-rays at a specified frequency range), but there have been documented cases of intensive ‘super’ storms (class ‘X’-level events) that can reach beyond our protective magnetosphere.



Shortly before noon on 1st September 1859 during the maximum period in the 10th Solar Cycle, the amateur astronomer Richard Carrington (and Richard Hodgson independently) began sketching a large sunspot region through his brass telescope when he observed an intensive, bright flash. His fortuitous observation would later be chronicled as the earliest confirmed sighting of the still-theorised solar flare, but his pivotal discovery would also be recalled as the most intensive geomagnetic storm encountered within recorded human history. Carrington studiously made note of his unique observations and began recording his full experience for later publication. After 17.6 hours had passed (i.e., the sufficient transit delay for the plasma cloud), the expelled CME material violently clashed against the Earth’s magnetosphere, stretching its protective shield tail towards breaking point. Ricocheting backwards after the magnetosphere tail snapped, the powerful influx of charged stellar material rapidly induced magnetic currents across the Ionosphere, thereafter translating this surplus energy into Geo-Magnetically Induced Currents (GICs) on the upper surface of our planetary crust. It was these GICs that created widespread electric disruptions across telecommunication systems and, in some cases, caused extensive damage to erstwhile networks. Consequently, Earth fell silent in the wake of this widespread disruption to telegraph lines. Damage, however, was ‘minimal’ given the limited global reliance on telegraph services at the time – electrical networks which bore the brunt of this ‘abnormal’ geomagnetic storm. Yet, the event continues to be cited as a cautionary tale to encourage crucial heliophysics research, electrical grid resiliency, and the implementation of other safeguarding measures to protect our modern high-tech macro-societies.


The uncomfortable truth, however, is that Solar Storms of varying intensity, and the impacts resulting from stellar flares and CME, are a common phenomenon encountered by the Earth’s magnetosphere. Concentrations of Carbon-14 within tree rings and Beryllium-10 (among other isotopes) in ice cores, alongside several other proxy resources, all paint a similar portrait of our planet; stellar material has long interacted with the past biochemistry of the terrestrial surface, and revisited quite often. This evidentiary well of Carbon-14 isotopes alone has been used to reconstruct the last 11,400 years of sunspot activity; furnishing us with a mere glimpse into the deep-time frequency of these geomagnetic storms, and their capability to continually influence and disrupt life on and

across the entire planet – from satellite disruptions and electronic interference, to the widespread implications of more damaging radiations. Yet, this snapshot of our planet’s history is far from a complete picture.

Since 1859, less-intense bursts of solar material have been documented to have interfered with terrestrial life over the succeeding modern decades. The volume ‘Solar Storms: 2000 years of human calamity’ explores many decades worth of these encounters in intricate detail, stitching together our recent history from the wide range of acute observations, perturbations experienced, and societal reactions across our planet for over two hundred years. For instance, in March 1989 a geomagnetic storm was responsible for disruptions to the entire power grid of Quebec City. In August 1972, a solar storm caused severe technological disruptions throughout North America and the Pacific regions, including the accidental detonation of over 4,000 U.S. magnetic-influence sea mines near North Korea, as well as triggering launch alerts on Vela nuclear detonation-detection satellites. A milder geomagnetic storm in February 2022 led to the failure, and destructive re-entry, of 40 SpaceX Starlink satellites. Numerous other solar storms of varying intensity between these documented ‘extreme’ instances have frequently pummelled our planet, triggering stronger auroral activity, while extending these dazzlingly vibrant lights downwards towards the equator. Surveillance by STEREO-A and other solar observatory satellites (like DISCOVR, SOHO, and GOES) have revealed that ‘Carrington-level’ geomagnetic storms are also much more common than previously assumed within our meagre window of recorded Solar Cycles; the Ultrafast CME on 23rd July 2012 being perhaps the most distinguished event, narrowly missing Earth by mere days (due to the Sun’s own rotation rate).


Solar storms are but one facet of ‘Space Climate’ that regularly reshapes the lives and lifestyles we enjoy on Earth today. Yet, these storms are perhaps the most significant local stellar phenomenon that may inflict serious damage to electronic systems on a global scale, disrupting the balances of social order and civil unity along with supply chain issues for vital resources (e.g., water pumps, power distribution services, etc.), while also incurring severe economic damage in the fallout for our globally interconnected civilisations. Geomagnetic storms are a regularand inescapable – property of our ‘stormy’ stellar neighbourhood, essentially guaranteeing Earth will encounter bombardments of flares and CME to varying degrees of intensity, and into perpetuity. Probability estimates vary for predicting the next Carrington-level geomagnetic storm occurring in the imminent decade – about 12% of a chance per year – but it is certainly a question of when, not if, and how prepared humanity will be for this fateful encounter. Some popular media outlets state that our world is overdue another Carrington-level flare, while others estimate events only occur

every 500 years, with a range of other probabilities calculations available. Yet, July 2012 CME calls into question these predictions.

In recognising these realities, our attention immediately sways toward questioning when the next CME will violently wash across our planet, and how prepared our civilisation already is for such an eventual calamity. Clearly, the most obvious victims of any large geomagnetic storm will be our fragile belts of astute satellites and the services they furnish us with, but other consequences are also predictable. A detailed 2013 risk assessment by Lloyds and AER (Atmospheric and Environmental Research) concludes that a Carrington-level geomagnetic storm is both inevitable, and may cause the catastrophic outage of the ageing United States power grid for anywhere between 16 days to 1–2 years, with an estimated cost of $0.6–2.6 trillion to repair all damaged transformers across the U.S. grid. Preventative measures that may mitigate widespread damage have been proposed (with expensive upfront costs), but ‘hardening the grid’ against such super storms has proceeded at a slower pace than desired. Moreover, advanced warning of an incoming violent solar storm provides mere hours of notice for a global ‘switch off’ of grids to avoid the most detrimental damage, but only if this event is observed and reported within sufficient timeframes. For this reason alone, numerous space agencies and ground institutes, including the SWPC and the U.S. Air Force, cast a near-constant gaze towards our nearby star, looking for any pre-emptive signs of an ‘Earth-directed’ stellar ejection. Learning to live with our ‘stormy star’ is perhaps the most prudent defensive measure we can hope to adopt, while mitigating steps continue to be pioneered against our Sun’s most disruptive impulses.



As part of the After the Horizon initiative, the foundation is presently compiling an extensive catalogue of historic solar storms, their measured intensities (if available), observational data (if available), perceived fallout across terrestrial environments (if available), and also general Solar Cycle statistics in the interest of both maintaining knowledge, and access to, these crucial resources for further scientific study. The ‘Solar Storms’ compendium is being cultivated as part of a concerted, multidisciplinary effort to preserve this crucial information for the benefit of future scientific investigations as our knowledge of local solar storms continues to mature with each bombardment we witness, and duly chronicle for posterity. The intention of this archive is principally custodial in nature, ensuring a ‘hard-copy’ of all materials and data remains available – and accessible – for sustained study of our in-situ stellar environment, no matter how else we chose to protect this data


Additionally, this cataloguing effort will hopefully establish a precedent for how to fold our extended observations of the Sun, and heliophysics in general, into the realm of other long-term experimental practices; providing vital observational data across generational scales for our local stellar body, while possibly conserving this information against the very phenomenon that may, one unfortunate day, irreparably damage digital resources for posterity (a ‘digital oblivion’ as sometimes described). This Solar Storm initiative is considered a counterpart compendium for our established ‘Climate Recording’ programme; conserving crucial environmental data that will not remain viable for future observations, or repeatable testing, as sampling sources (such as ice cores, and dendrochronology) naturally degrade over time. Much of our history of Solar activity hails from these very same sources.

Notes to the catalogue: The index simply documents materials that have been recorded by a number of historical archives, journalists, academics, instrumentation experts, and also contemporary space agencies for the purposes of heliophysics research. Any large divergences in figures are noted after the defined ‘formally-accepted’ observation data; properties agreed upon by an established majority of observational institutes. No judgements or independent assessments for the risk profile associated with any of the listed solar storms have been completed, nor does the foundation actively employ observational instrumentation for heliophysics studies. The entire catalogue remains an active document, subject to updates, amendments, and further peer-review, in addition to the inclusion of future observational data for the next significant solar storms that precariously hurdle towards Earth.

Page last updated: 05 May 2023

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