May 2024 Geomagnetic Storms: Historic Auroras

15 Maio 2024

Escrito por Francisco H. C. Felix

In May 2024, Earth was struck by a series of intense geomagnetic storms Geomagnetic Storm: A geomagnetic storm is a temporary disturbance of Earth’s magnetic field caused by solar activity, such as CMEs or solar flares. These storms can disrupt technology, navigation, and create auroras far from the poles. triggered by powerful coronal mass ejections (CMEs) Coronal Mass Ejection (CME): A CME is a massive burst of solar wind and magnetic fields released from the Sun’s corona into space. When directed toward Earth, CMEs can trigger geomagnetic storms, affecting satellites, power grids, and producing auroras at unusual latitudes. from the Sun. These storms produced auroras Aurora: An aurora is a natural light display in Earth’s sky, usually seen in high-latitude regions. Auroras are caused by charged solar particles interacting with Earth’s magnetic field and atmosphere, producing colorful lights. visible at exceptionally low latitudes, including parts of the United States, Brazil, Europe, and even North Africa. The phenomenon was widely documented by observers and scientists, marking one of the most significant space weather events of the 21st century.

Between May 8 and 14, 2024, an active region Solar active region: is a location in the Sun’s atmosphere with a significant increase in the intensity and complexity of its magnetic field, usually seen as a sunspot region. These regions are often associated with solar phenomena such as solar flares and coronal mass ejections, which can have significant impacts on space weather and technology on Earth. Active regions are generally hotter and brighter than the surrounding areas of the Sun. of the Sun, AR3664, produced a series of intense solar flares Solar Flare: A solar flare is a sudden flash of increased brightness on the Sun, usually near sunspot groups. Flares release large amounts of energy and particles into space, sometimes leading to geomagnetic storms on Earth. and CMEs. As a result of the high density and speed of the solar wind Solar wind: is a continuous flow of charged particles, mainly protons and electrons, ejected from the Sun’s corona. These particles travel through space at speeds ranging from 300 to 800 km/s, depending on solar activity. The solar wind is responsible for various phenomena in space, including interaction with Earth’s magnetosphere, which protects the planet from cosmic radiation and solar particles. During periods of high solar activity, such as solar flares or coronal mass ejections, the solar wind can intensify, causing geomagnetic storms that affect satellites, power grids, and communications on Earth. , and the interplanetary magnetic field Interplanetary magnetic field: is the magnetic field that permeates the space between the planets of the solar system. It is mainly generated by the Sun and is an extension of the solar magnetic field, which stretches beyond the heliosphere, the region dominated by the solar wind. The interplanetary magnetic field influences the movement of charged particles in space, affects space weather conditions, and interacts with the magnetic fields of planets, including Earth. This field is crucial for protecting Earth against cosmic radiation and solar particles, and also plays an important role in the formation of auroras and other space phenomena. reaching extreme values, along with the interaction of the CMEs with the geomagnetic field Geomagnetic field: is Earth’s magnetic field, generated by the movement of the planet’s liquid outer core, mainly composed of iron and nickel. This magnetic field extends from Earth’s interior into space, forming a region called the magnetosphere, which protects the planet from charged particles of the solar wind and cosmic radiation. The geomagnetic field is crucial for navigation, as it guides compasses and influences communication systems and satellites. It also plays an important role in the formation of auroras when solar particles interact with Earth’s atmosphere. Its average value at the surface is 25 to 65 µT (microtesla) and varies over time due to changes in Earth’s core and solar activity, being monitored by several scientific agencies worldwide. , an intense geomagnetic storm occurred.

Aurora seen in Pawleys Island, South Carolina, U.S. (33°N GLAT, 43°N MLAT) May 11, 2024. Source: Wikipedia

Aurora seen in Quillón, Chile (36°S GLAT, 24°S MLAT), May 11, 2024. Source: Wikipedia

Aurora seen in Mazatlán, Mexico (23°N GLAT, 31°N MLAT), May 11, 2024. Source: Wikipedia

Aurora in Algeria, May 11, 2024 Aurora seen in Algeria, May 11, 2024. Source: ArabiaWeather.com

Aurora seen in Melbourne, Australia (38°S GLAT, 48°S MLAT), and in Cwmbran, Wales, U.K. (51°N GLAT, 47°N MLAT), May 11, 2024. Source: Wikipedia

What are geomagnetic storms?

Geomagnetic storms are disturbances in Earth’s magnetic field caused by interactions with highly energetic solar particles, especially during CMEs. They can disrupt communications, power grids, satellites, and even cause auroras at unusual latitudes.

Comparison with historic events

The May 2024 storms were classified as G5 (extreme) by NOAA SWPC, with Kp Kp Index: The Kp index is a scale from 0 to 9 that measures the global intensity of geomagnetic activity. Higher Kp values mean stronger geomagnetic storms and a greater chance of seeing auroras at lower latitudes. indices reaching 9. For comparison:

Carrington Event (1859): The largest geomagnetic storm ever recorded, causing telegraph failures and auroras as far south as the Caribbean.

Quebec Storm (1989): The most intense geomagnetic storm of the modern era, recorded by various measurement methods. Caused a blackout in Canada and auroras at mid-latitudes.

May 2024 Storms: Auroras seen as far south as southern Brazil and Texas, with reports of power grid and navigation disruptions.

Event	Year	Max Kp	Main Impact
Carrington	1859	9+	Telegraph failures, tropical auroras
New York Railroad	1921	9	Railroad fires, telegraph/telephone outages
Quebec	1989	9	Blackout, mid-latitude auroras
Halloween Storms	2003	9	Satellite, GPS, aviation disruptions
May 2024	2024	9	Low-latitude auroras, power disruptions
March Storm	1989	9	Power grid failures, auroras
May Storm	1921	9	Telegraph/telephone outages, fires
August Storm	1972	8-9	Satellite, communication disruptions
July Storm	1958	9	Auroras at low latitudes
September Storm	1941	9	Telegraph/telephone outages, auroras

Historical Section: The Carrington and Quebec Events

The Carrington Event (1859)

The Carrington Event is considered the most powerful geomagnetic storm ever recorded. On September 1, 1859, British astronomer Richard Carrington observed and drew a massive group of sunspots, followed by a sudden bright flash (solar flare). This was the first time a solar flare was directly linked to geomagnetic disturbances on Earth.

Richard Carrington’s drawing of the sunspots, 1859. Source: Wikipedia

Within just 17 hours, a CME reached Earth, causing auroras visible as far south as the Caribbean and northern South America. Telegraph systems across Europe and North America failed, with some operators receiving electric shocks and telegraph paper catching fire. Some systems continued to operate even when disconnected from their power supplies, powered by geomagnetically induced currents.

About Richard Carrington: Richard Christopher Carrington (1826–1875) was a pioneering English astronomer who made significant contributions to solar physics. His observations in 1859 provided the first evidence of a direct connection between solar activity and geomagnetic storms on Earth.

The Quebec Storm (March 1989)

The Quebec geomagnetic storm occurred on March 13, 1989, and is one of the most significant space weather events of the modern era. Triggered by a powerful CME, the storm caused a nine-hour blackout in the Canadian province of Quebec, leaving six million people without electricity. The event also disrupted satellites, radio communications, and caused auroras as far south as Texas and Florida.

GOES-7 monitors the space weather conditions during the Great Geomagnetic storm of March 1989. The Moscow neutron monitor recorded the passage of a CME as a drop in levels known as a Forbush decrease. Source: Wikipedia

Repercussions:

Power grid transformers were damaged in Canada and the US.
Satellite operations were disrupted, and some satellites tumbled out of control.
Shortwave radio and navigation systems experienced outages.
The event led to major investments in space weather monitoring and grid protection.

Dates involved:

March 9, 1989: Solar flare and CME observed.
March 13, 1989: Geomagnetic storm and blackout in Quebec.

What if a Carrington-level event happened today?

A storm of Carrington magnitude could cause widespread blackouts, damage to transformers, satellite failures, GPS and communication disruptions, and economic losses in the trillions of dollars. Modern society is far more dependent on electricity and technology than in 1859, making us more vulnerable to such events.

Studies estimate that Carrington-class storms have a probability of about 1–2% per decade (roughly once every 50–100 years). While rare, the risk is significant enough that governments and utilities are investing in monitoring and mitigation strategies.

Space Weather Monitoring and Its Importance

Space weather monitoring is crucial for protecting modern technological infrastructure from the effects of geomagnetic storms. Several national and international agencies operate space weather monitoring and alert systems:

NOAA Space Weather Prediction Center (SWPC, USA): The main agency in the US for space weather forecasting, monitoring, and alerts. Provides real-time data, warnings, and educational resources.

ESA Space Weather Office (Europe): The European Space Agency coordinates space weather monitoring and research across Europe.

UK Met Office Space Weather Operations Centre (UK): Provides forecasts and alerts for the UK and collaborates internationally.

National Institute of Information and Communications Technology (NICT) - Japan: Monitors solar and geomagnetic activity in East Asia.

Other agencies: Canada, Brazil, Russia, China, Australia, and 14 other countries also maintain space weather programs.

These agencies share data and collaborate through the International Space Environment Service (ISES), a global network for space weather information exchange.

Space Weather Alert Programs

Most agencies operate public alert systems that notify utilities, satellite operators, airlines, and the public about ongoing or forecasted space weather events. Alerts use standardized scales:

Kp Index: A global index of geomagnetic activity from 0 (very quiet) to 9 (extremely disturbed). Kp values of 5 or above indicate a geomagnetic storm.

G Scale (NOAA): The US SWPC uses the G scale to classify geomagnetic storms:

G Level	Description	Kp	Typical Effects
G1	Minor	5	Weak power grid fluctuations, minor satellite impact, auroras at high latitudes
G2	Moderate	6	Possible voltage alarms, transformer damage at high latitudes, auroras at mid-latitudes
G3	Strong	7	Voltage corrections needed, false alarms on protection devices, auroras as far south as Texas/Brazil
G4	Severe	8	Widespread voltage control problems, possible transformer damage, auroras as far south as southern US/Europe
G5	Extreme	9	Widespread power grid problems, possible system collapse, auroras seen in tropical regions

These scales help communicate the severity and possible impacts of geomagnetic storms to decision-makers and the public.

Conclusion

The geomagnetic storms of May 2024 will be remembered as one of the greatest natural spectacles of the century, highlighting the importance of space weather monitoring and preparedness for its impacts on our technological society.