Summer read: Cosmic Catastrophes

When it comes to a relaxing summer read, The Little Book of Cosmic Catastrophes (That Could End the World) might not be the kind of title that springs to mind. But this tongue-in-cheek, hilariously morbid approach to astronomy could actually be the fun read you’re looking for!

Written by the bright and bubbly science communicator, Dr Sara Webb from Swinburne University of Technology in Melbourne, Victoria, the material is entertaining and educational. It’s an easy read but doesn’t shy away from including those maths equations you’re keen to check out.

Cosmic Catastrophes is compact and beautifully designed. It will slide into your bag easily, ready to accompany you on your holiday travels.

There are plenty of fun, bite-sized facts to share with the family. Even better, it covers topics that are less likely to cause a stir than the usual political fanfare accompanying that conspiracy-spouting relative you’re forced to endure once a year.

Check out an excerpt from the book below.

Death rays from the Sun

Death rays from the Sun are not the most comfortable idea.

But fear not – they aren’t quite as bad as the death rays from space. Let’s begin with a story from history…

In 1859, astronomers were beginning to uncover the secrets of the universe.  Observatories and telescopes were being built around the world. Astronomers weren’t just interested in the stars in the night sky, they were also fascinated by the rather impressive one in our daytime sky. One amateur astronomer, Richard Carrington, took great care and time to look at the Sun through a solar telescope and he painstakingly drew what he saw. Carrington was interested in why the surface of the Sun wasn’t constant – dark spots appeared on it from time to time.

On 1 September 1859, Carrington was sketching a large area of the Sun that had multiple interesting sun spots. As he worked, he saw a bright flash of light. At first he thought his viewing set-up had failed, but he quickly realised that the flash was very real. The increased brightness only lasted a couple of minutes. Carrington wasn’t the only person to see this event. Another amateur astronomer, Richard Hodgson, was also observing the Sun and noticed the same remarkable increase in brightness. What both men had witnessed was a large white light solar flare. But what they didn’t know was that a massive amount of material had been ejected from the Sun and was heading directly towards Earth.

In the early hours of 2 September 1859, reports started to trickle in from around the globe that something strange was occurring in the sky – dancing ribbons of lights in brilliant greens, reds and blues. They were auroras, but at extremely low latitudes. Auroras are usually only visible near the north and south poles. This light show was both spectacular and haunting to those witnessing it. That mass ejection from the Sun had finally reached Earth and our magnetic protector – the magnetosphere – was working overtime.

The Carrington Event, as it is now known, was the largest geomagnetic storm ever recorded in human history. The Sun ejected billions of kilograms of highly charged plasma almost directly towards Earth. If it wasn’t for our magnetic field and atmosphere, the full force would have hit the surface of Earth. Instead, the charged particles were essentially trapped above us, causing those stunning auroras. However, the most frightening thing about geomagnetic storms is the chaos they can create on the surface of the planet.

To explain this, let’s look at one of my favourite principles in physics – Faraday’s law.

Faraday’s law describes how magnetic fields interact with electric circuits to produce electromotive force. In plain language, this means that when a magnetic field is changed around a circuit, electrons in that circuit start moving. The really cool thing is that we use it every day. Do you have an induction stovetop? That’s Faraday’s law. Do you charge your phone or watch wirelessly? Faraday’s law again!

These are small-scale examples, but this can also happen on the scale of Earth. And that is exactly what occurred on 2 September 1859. Earth’s magnetic field was highly affected by the increase in charged particles, and it was enough to induce electrical currents on the ground. In 1859, it didn’t cause smartphones to charge unexpectedly but, almost instantly, 160,000 kilometres of telegraph lines felt silent. Entire telegraph systems were fried and some operators even experienced electric shocks. It was a communication blackout caused by the chaos unfolding in Earth’s magnetosphere.

The telegraph operators quickly turned off all power to the systems and waited for things to settle down. However, some lines remained open and signals were transmitted purely on the current induced from the skies. One conversation between Boston and Portland literally made the history books.

Sept 2, 1859

Boston:

Please cut off your battery [power source] entirely for fifteen minutes.

Portland:

Will do so. It is now disconnected.

Boston:

Mine is disconnected, and we are working with the auroral current. How do you receive my writing?

Portland:

Better than with our batteries on. Current comes and goes gradually.

Boston:

My current is very strong at times, and we can work better without the batteries, as the aurora seems to neutralise and augment our batteries alternately, making current too strong at times for our relay magnets. Suppose we work without batteries while we are affected by this trouble.

Portland:

Very well. Shall I go ahead with business?

Boston:

Yes. Go ahead.

It was a remarkable event, and it may happen again. It’s not unusual for the Sun to flare and have coronal mass ejections.

The Sun is a big, complicated system. Fusion rages in its core, fusing hydrogen into helium. Around the core sits the radiative zone, a massive region where the light produced by fusion is carried slowly towards the surface. It can take millions of years for photons to leave this area. The surface of the Sun, which we can see through telescopes, is called the convective zone. This is where hot plasma bubbles away – the hottest bits move towards the surface and the cooler bits fall back down towards the core.

The Sun has an extremely powerful magnetic field. We can see traces of it in images as particles travel along the magnetic field lines beyond the surface. This magnetic field is caused by a dynamo, but unlike Earth’s, it isn’t made of molten metals. Specifically, we think the Sun has a magnetohydrodynamic dynamo. (That is a big word that is fun to say – mag-neto-hydro-dynamic.) This means that the plasma rotating in a complicated system inside the Sun is creating a magnetic field. Like a bar magnet, a magnetic field has a north and south, but unlike a bar magnet, north and south can flip.

In the Sun, this happens roughly every 11 years. There is an increase in solar activity, including sun spots, flares and coronal mass ejections, just before the poles flip. This period is called a solar maximum. The Carrington Event took place during a solar maximum, only a few months from a geomagnetic reversal.

The good news is that the Carrington Event appears to have had no lasting effects on Earth. The bad news is that this might not always be the case. The Carrington Event was rare, but we actually expect to see similar events every 500 years or so. But what’s the worst that could happen?

Let’s imagine a Carrington-level event in 2359.

The internet is carried solely via satellites, which are cheaper and more efficient than maintaining cables. Self-driving vehicles use GPS, satellite images and artificial intelligence (AI) to make decisions about their routes. Autonomous mining and agricultural machines use AI and data from satellites to determine what they do. We’ve moved to renewable energies and solar panels are widely used.

We are alerted that there has been a massive solar flare. A coronal mass ejection is heading our way and will hit Earth in 18 hours. To protect our satellites, we power some of them down and put them into safe orbits. Many parts of the world lose internet access during that time. Solar panels are also powered down, as are some power grids, meaning some areas of the world experience power outages.

As the material hits the magnetosphere, the atmosphere experiences more pressure and the orbits of satellites are affected. The satellites that have been powered down can’t make AI-informed manoeuvres and some of them collide. These collisions create a runaway chain of debris and more and more satellites are affected. Millions of people are watching stunning auroras play out above them, but it’s complete chaos in the sky. Even with the power off in many cities, the currents induced by the geomagnetic storm cause damage to electric grids and some systems take weeks to repair. Self-driving AI transport is heavily affected by lack of access to the internet and uncertain GPS data. Farming and mining are halted for the same reasons.

People on the ground are initially unharmed by the solar flare, but as hours, days and weeks pass, the lack of access to the internet, transport and fresh produce causes mass hysteria. In some cities, rioting and looting occur as people struggle for supplies. The damage to systems in space and on the ground effectively sets human civilisation back to a pre-technological age. It might take decades to rebuild.

Even in this worst-case scenario, Earth remains fine. The magnetosphere bounces back and the atmosphere remains intact. And by 2359 it’s likely that we will have developed new materials that are super-hard and can withstand heavy doses of radiation. Most of our satellites wouldn’t even bat an eye at a Carrington-level event geomagnetic storm. Our ground systems would also likely have protocols in place to limit the damage to solar panels and powerlines. Good news!

Of course, there is always the chance that the Sun will surprise us with an event 100 times more powerful than the Carrington Event. This could do a little more damage, but it would not end the world as we know it. It would be exceptionally rare – probably once in thousands of years – so we can write it off (for now) as unlikely.

Dr Sara Webb is an astrophysicist and science communicator, based at Swinburne University of Technology. Her latest book is called The Little Book of Cosmic Catastrophes (That Could End The World).