#346 What was the Carrington Event?

What was the Carrington Event? It was the largest ever geomagnetic storm in recorded history?

The Carrington Event lasted from the 1^st to the 2^nd of September 1859. It was observed by an amateur astronomer called Richard Christopher Carrington; hence its name, and it was caused by a very bright solar flare. From August of 1959, the number of spots on the surface of the sun built up until there was a sudden flash of light that lasted about five minutes.

This flash of light was a coronal mass ejection (CME). A CME is caused by an instability in the sun’s magnetic field. The sun has a magnetic field in the same way as the Earth does, but it is obviously far bigger and far stronger. The sun is a liquid ball of plasma and the plasma on the surface of the sun is held in by the magnetic field. As the plasma swirls around, it causes turbulence that twists the magnetic field, and it reaches a point where it suddenly snaps. Before the field can reform, a CME happens. The plasma bursts out and heads into the solar system at about 3,000 km/s. About a billion tons of plasma, which is made up of protons and electrons, fly out of the sun. CMEs happen several times a day, but they very rarely head in our direction. We tend to get hit by one about once every 25 years.

Earth is constantly hit by the solar wind. This is a stream of charged particles that are released from the atmosphere of the sun. These particles bounce off our magnetic field and cause the aurora lights. Some of the particles get through our magnetic field, but not enough to do any damage. A CME travels much faster than the solar wind and has far more material in it. It takes about 13 hours for material emitted from a CME to reach Earth. If the plasma hits Earth at an oblique angle, it would still bounce off into space, but if it hits straight on, it causes a geomagnetic storm. The plasma hits our magnetic field on the side facing the sun and the shockwave compresses it. On the far side of Earth, the magnetic field stretches out and separates. The magnetic field picks up terawatts of power from the solar plasma and when the tail end of the magnetic field reconnects, this power flows back into Earth’s upper atmosphere along the magnetic field lines. This extra electricity in the atmosphere can disrupt power grids, damage satellites, destroy communication networks, and anything else that uses electricity. A CME in 1989 knocked out all of the power in Quebec for nine hours.

So, what was the Carrington Event? On September 1^st, 1859, Richard Carrington was in the UK observing the growing number of sunspots. At 11:18 AM, he saw the bright sun flare that lasted about ten minutes. Magnetic sensors in London detected a huge increase in magnetic activity. Carrington realized that it must be coming from the sun flare he saw. The data shows that it was the largest geomagnetic storm that Earth has experienced in recorded history.

The CME hit Earth causing aurorae in the atmosphere. Apparently, they were bright enough to read by and there is an account of gold miners waking up at 1 AM to cook breakfast because they thought the sun had risen. Aurorae are usually limited to around the poles, but these aurorae stretched all the way to close to the equator. The CME damaged telegraph systems all across Europe and North America. These telegraph systems weren’t very old and were still in their early days. Sparks flew off the pylons and operators were able to send messages even after switching off the power. Some operators received electric shocks off the equipment. The phenomena lasted for about a day and had passed by the end of September 2^nd.

Hugh Hudson, a solar physicist at the University of Glasgow, has calculated that the CME of the Carrington Event carried about the same amount of energy as 10 billion megaton nuclear bombs into the atmosphere. I have no idea how much power that is, but it is a lot.

What would happen if something like the Carrington Event hit us today? We are far more dependent on electricity and technology than people were 160 years ago. Lloyds of London has estimated that an event like the Carrington Event today would cause about $2.6 trillion in lost revenue for the power industry in North America alone. Blackouts could stretch on because the CME would cause a domino effect of disruptions to financial markets, banking, telecommunications, business, and emergency services all at the same time.

Scientists think that the sun has CMEs that are much more powerful than the Carrington Event quite often. 10 times more powerful are once every 3,000 years and 100 times more powerful are once every 6,000 years. Not sure what we will do if that hits us. And this is what I learned today.

Sources

https://pwg.gsfc.nasa.gov/istp/nicky/cme-chase.html

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

https://www.sciencealert.com/destructive-super-solar-storms-usually-hit-us-four-times-a-century

https://education.nationalgeographic.org/resource/sun