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The Sun Is Hitting a Phenomenal 11-Year Peak, And The Effects Could Be Huge : ScienceAlert

Many more people than normal around the world were recently able to see the northern and southern lights with the naked eye. This unusual event was caused by a very strong solar storm, which affected the movement of the Earth’s magnetic field.

The Sun is reaching its peak of activity in an 11-year cycle. This means we can expect more explosive eruptions of particles.

Under the right circumstances, these are what ultimately generate the beautiful auroras in the sky, as well as the geomagnetic storms that can damage infrastructure such as power grids and orbiting satellites.

So what is really happening to cause these phenomena? The northern and southern lights are usually confined to very high and very low latitudes. High-energy particles from the Sun flow toward Earth, guided by the Sun’s magnetic field. They are transferred to the Earth’s magnetic field in a process known as reconnection.

These really fast, hot particles then race down the Earth’s magnetic field lines (the direction of a magnet’s force) until they collide with a cold, neutral atmospheric particle like oxygen, hydrogen, or nitrogen. At this point, some of that energy is lost and this warms the local environment.

However, atmospheric particles do not like to be energetic, so they release some of this energy in the visible light range. Now, depending on which element is too hot, you will see a different set of wavelengths (and therefore colors) emitted in the visible light range of the electromagnetic spectrum.

This is the source of the auroras that we can see at high latitudes and, during strong solar events, also at lower latitudes.

The blues and purples of the aurora come from nitrogen, while the greens and reds come from oxygen. This particular process happens all the time, but because Earth’s magnetic field is shaped like a bar magnet, the area that receives energy from the incoming particles is located at very high and low latitudes (the Polar Circle). Arctic or Antarctica in general).

So what happened to allow us to see the aurora much further south, in the northern hemisphere?

You may remember that in school you would spread iron filings on a piece of paper on top of a magnet to see how they aligned with the magnetic field. You can repeat the experiment several times and see the same shape each time.

The Earth’s magnetic field is also constant, but it can compress and release depending on the strength of the Sun. A simple way to think about this is to imagine two half-inflated balloons pressed together.

If you blow up a balloon and add more gas, the pressure will increase and push the smaller balloon back. As you release that extra gas, the smaller balloon relaxes and pushes outward.

For us, the stronger this pressure is, the closer to the equator the corresponding magnetic field lines approach, which is why auroras can be seen.

Exceptional storms

This is also where potential problems come in: a moving magnetic field can generate a current in anything that conducts electricity.

In modern infrastructure, the largest currents are generated in power lines, train tracks and underground pipes. The speed of this movement is also important and is tracked by measuring how perturbed the magnetic field is from “normal.” One such measure used by researchers is called the disturbed storm weather index.

By this measure, the geomagnetic storms of May 10 and 11 were exceptionally strong. In such a strong storm there is the potential danger of electrical currents being induced.

Power lines are most at risk, but have benefited from protections built into power plants. These have been in the spotlight since the 1989 geomagnetic storm that melted a power transformer in Quebec, Canada, causing hours of power outages.

Metal pipes that corrode when an electric current passes through them are at greater risk. This is not an instantaneous effect, but rather there is a slow buildup of eroding material. This can have a very strong effect on the infrastructure, but it is very difficult to detect.

While currents on the ground are a problem, they are even more so in space. Satellites have a limited amount of grounding and an electrical surge can destroy instruments and communications.

When a satellite loses communications in this way, it is known as a zombie satellite and is often lost completely, resulting in a very high investment loss.

Changes in the Earth’s magnetic field can also affect the light that passes through it.

We can’t see this change, but the accuracy of the GPS-style location system can be greatly affected, since the location reading depends on the time between your device and a satellite. The increase in electron density (the number of particles in the signal path) causes the wave to bend, meaning it takes longer to reach your device.

The same changes can also affect satellite Internet bandwidth speeds and the planet’s radiation belts. It is a torus of high-energy charged particles, mostly electrons, about 13,000 kilometers away from the surface.

A geomagnetic storm can push these particles into the lower atmosphere. Here, particles can interfere with high-frequency (HF) radio used by aircraft and affect ozone concentrations.

Auroras are not confined to Earth: many planets have them and they can tell us a lot about the magnetic fields that exist in those celestial objects. One particular device used to simulate auroras is a “planeterella”, first developed in the early 20th century by Norwegian scientist Kristian Birkeland.

A magnetic sphere (representing the Earth) is placed in a vacuum chamber and the solar wind is simulated by shooting electrons into the sphere. We have two of these instruments in the UK within universities and here at Nottingham Trent University I recently helped a student create a budgeting version as a masters project.

By altering the intensity of the magnetic field and the distance between objects, you can observe how the auroras change. The emission is mostly violet, as expected in an atmosphere with 72% nitrogen.

A strong ring of emission appears around the top, where the aurora would be seen on Earth, and this ring moves up and down in latitude depending on the strength of the magnetic field.

As a natural event, the auroras are a marvel. But even better is that with every strong geomagnetic storm, we make improvements that help protect against potential damage from future events.The conversation

Ian Whittaker, Senior Lecturer in Physics, Nottingham Trent University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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