Science

The Carrington Event: The Greatest Solar Storm in History

The Carrington Event was a major solar storm that occurred in early September 1859, just a few months before the 1860 solar maximum. In August 1859, astronomers around the world watched with admiration as the number of sunspots increased. Among them was Richard Carrington in Redhill, Surrey, UK.

Luckily for life on Earth, the Sun is surprisingly constantly radiating heat and light. However, it can also eject matter into space, although these ejections have gone undetected for most of human history.

Known as space weather, these phenomena, known as space weather, could now have serious consequences for the satellites and other electronic technologies we rely on, according to the European Space Agency (ESA).

According to a NASA Earth Observatory article, the origin of space weather can be traced back to distortions in the Sun’s magnetic field, resulting in dark patches or spots on its surface.

It is from these places that solar flares, coronal mass ejections and other electromagnetic phenomena can originate – with potentially dangerous consequences for our technological way of life.

Sunspot activity rises and falls over an 11-year cycle, and we are currently approaching the next solar maximum in 2025. So now is the time to take a look at the strongest solar storms.

What is a solar storm?

While space weather ultimately occurs on the Sun, the term “solar storm” refers to events on or near our own planet when material ejected by the Sun reaches us. There are two different types of solar storms: geomagnetic storms and solar radiation storms.

The first of these occurs when a clump of solar material called a coronal mass ejection (CME) disrupts the Earth’s magnetic environment. The second refers to the stream of much faster moving particles ejected by the sun.

As dangerous as the latter sounds, we are largely protected from its effects by the geomagnetic field, as are most satellites in Earth orbit. As a consequence, solar radiation storms are only really a problem for deep space missions.

Carrington event

In Sept. 1, when Richard Carrington was sketching sunspots, he had the good fortune to see a sudden flash of light – a solar flare – emanating from them. It was almost certainly accompanied by a CME because the Earth experienced an unprecedented geomagnetic storm the next day when telegraph systems went down and auroras, usually confined to northern latitudes, were visible in the tropics, according to a NASA Science article.

Carrington put two and two together and realized that the solar flare he was seeing was almost certainly the cause of this massive geomagnetic disturbance. It was a connection never seen before, according to a NASA Spaceflight article. The solar storm of 1859 is now known as the Carrington Event in his honor.

Drawing by Richard Carrington of sunspots at the peak of the Carrington Event in 1859. (Image credit: Richard Carrington)

coronal mass ejections

According to the National Oceanic and Atmospheric Administration’s (NOAA) Space Weather Prediction Center, the largest CMEs can contain billions of tons of solar material and fly away from the Sun at speeds up to 3,000 kilometers per second.

They contain a built-in magnetic field, and it is this that can wreak havoc on the Earth’s own magnetic field if and when it comes into contact.

We know that this has been happening since time immemorial; A study published in January 2022 found that a massive solar storm that hit Earth 9,200 years ago left radioactive particles in the ice deep below Greenland that are still there to this day, Live Science reports.

An earlier study in 2020 found that strong geomagnetic storms have occurred in 42 of the previous 150 years, much more often than previously thought.

Solar storm effects

NOAA rates geomagnetic storms on a scale from G1, which causes increased auroral activity and minor fluctuations in power supply, to G5, which includes extreme events such as the Carrington event.

In the middle of the scale, G3 “storm warnings” are relatively common; one was at the end of March 2022. Even a G2 event has the potential to cause havoc, like when SpaceX lost 40 satellites in February 2022 when a G2 storm prevented them from reaching their intended altitude.

A composite image of the sun taken by the Solar Orbiter spacecraft in March 2022. (Image credit: ESA)

Are solar storms dangerous?

While solar storms rarely pose an immediate threat to human life, there is a risk that they can affect safety-critical systems through electromagnetic effects ranging from space-based communications, navigation and weather forecasting services to ground-level power distribution, according to ESA’s Space Weather. Network service.

It has been suggested that a storm of the magnitude of the Carrington event, if it occurs today, could trigger an internet apocalypse by sending large numbers of people and businesses offline. For this reason, the UK government lists adverse space weather as one of the most serious natural hazards on its National Risk Register, and companies have contingency plans in place, provided they have enough warnings about them.

Additional Resources

How likely is another Carrington event? You can read about a recent study that evaluated the answer to this question at EarthSky.org. In addition, you can learn more about the Carrington event on the South African National Space Agency (SANSA) website.

Bibliography

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