Rebel Star Our Quest to Solve the Great Mysteries of the Sun

In 1869, a great mystery was born. As astronomers observed a total solar eclipse, for the first time they saw the faint glow of the solar corona, the sun’s outer atmosphere. Measurements of a previously unknown wavelength that made up this solar light sparked hot debate among scientists, but it was another 60 years before they discovered that this wavelength was in fact iron being burned at a staggering 3 million degrees Celsius. With the sun’s surface only 6,000 degrees, this shouldn’t be possible. What we now knew about the sun appeared to defy the laws of physics—and nature. But as well as being shrouded in intriguing mystery, the unpredictable nature of the sun’s corona poses a serious threat to our life here on earth—the destructive potential of solar storms, caused by solar material traveling out into space at around 1 million miles an hour, is huge. Remaining beyond our reach until now, a new generation of ambitious solar missions are currently traveling closer to the sun than any previous spacecraft in history. As we enter this unprecedented era of heliophysics, there has never been a better time to get to grips with the workings of our home star. Rebel Star is a timely and essential guide, examining our long-held fascination with the sun, from ancient beliefs, to early scientific studies, and an up-to-date look at what we know—and still don’t know—taking us on a thrilling journey to the center of our solar system.

Colin Stuart is an astronomy journalist and author. He has written for the Guardian, European Space Agency and New Scientist, and is a Fellow of the Royal Astronomical Society. He has also recently had an asteroid named after him. He is the author of 13 Journeys Through Space and Time and How to Live in Space.
 

REBEL STAR
Chapter Breakdown

Introduction

Chapter 1: Superstition to science
A look at the importance of the sun in the history of humanity and how careful experiment and precise reasoning have morphed our understanding from superstitious hearsay to concrete science.

Chapter 2: Unweaving the rainbow
Not until the 1800s and the advent of spectroscopy did we have a way to nail down the true nature of the sun. By breaking up sunlight into the colours of the rainbow and teasing out the presence of subtle dark lines we were able to launch into a new era of solar physics.

Chapter 3: A star is born
Around 4.6 billion years ago the shockwave from a dying star slammed into a dark, cold cloud of cosmic dust. That sent it rapidly contracting in a runaway process that saw temperatures and pressures soar. Pockets within this 'nebula' became so dense and hot that a suite of new stars lit up, casting illumination around the surrounding gas. Atoms that had once been inside other stars now found themselves recycled into a fresh new one: the sun.

Chapter 4: A nuclear powerhouse
What powers the sun? The search for an answer took up the majority of the twentieth century. There were many twists and turns along the way. It's a story of war, intrigue, espionage and the search for the invisible.

Chapter 5: The epic journey of sunlight
Lay out in the sun and you're bathing in the light from a nuclear furnace casting heat 150 million kilometres across the solar system. This illumination – which feeds plants, drives the weather and lights up the sky – has been on the most remarkable of adventures. It began its journey 100,000 years ago deep in the core of the sun, which is where our story starts.

Chapter 6: Sunspots and the solar cycle
Light is not the only thing to make it up through the convection zone. The sun's surface is often pock-marked with sunspots and we've been speculating about their origins for centuries. One visionary astronomer finally proved they are linked to the sun's magnetic field emerging from
the deep.

Chapter 7: Flares, filaments and faculae
Sunspots aren't the only symptom of the sun's intense magnetic activity. As sunspots move around they can link up and trigger a colossal release of energy: solar flare. Only recently have astronomers been able to model these impressive events for the first time. A group of sunspots is known as an active region and the number of different events associated with them is dizzying. Huge prominences bigger than the Earth stretch far into space.

Chapter 8: The corona
Perhaps the sun's ultimate mystery is why temperatures in its outer layer – the corona – suddenly start to rise again after cooling as you move out from the core. It's baffled astronomers for 60 years. The corona can only be studied if you block out the main glare of the sun. Until recently we had to rely on solar eclipses and the moon shielding the sun on our behalf. Now we create artificial ones using spacecraft. NASA's Parker Probe and ESA's Solar Orbiter will be game changers as they plunge in to ‘touch’ the sun. The solar data pouring back to Earth in the coming years will be unprecedented.

Chapter 9: The solar wind
The sun's influence does not stop at the corona, though. Our star is constantly gusting a stream of charged particles into the solar system known as the solar wind. It rages outwards at more than a million kilometres an hour, but it is unclear how the particles are accelerated to move that quickly.

Chapter 10: Living in the sun's atmosphere
The sun may be 150 million kilometres away, but its magnetic tendrils reach right out to the Earth and beyond. It's more accurate to think of Earth existing and embedded in the sun's outer atmosphere. Here we'll look at interactions between solar material and the Earth's magnetic field – a marriage that generates both the spectacular and the staggeringly dangerous.

Chapter 11: The heliosphere and the gateway to interstellar space
Ours isn't the only planet with enchanting aurorae – Jupiter and Saturn sport impressive polar displays, too. In fact, the sun's magnetic influence continues to dominate the solar system way out beyond the planets, where its light fades to less than 0.1 per cent of the illumination we receive on Earth.

Chapter 12: The sun and the Milky Way
Just as the planets orbit around the sun, so the sun orbiting around the centre of our Milky Way galaxy. Only recently have we begun to understand the intricacies of this journey and how it might affect us here on the Earth. Our galaxy is also thought to be filled with an invisible glue known as dark matter. The sun should be vacuuming up some of it as it careers around. We'll hear about the latest experiments designed to pick up dark matter reactions occurring deep inside the sun.

Chapter 13: The sun's ultimate destiny
Nothing lasts for ever. Even something as steadfast to us as the sun has an expiry date. Eventually the sun will run out of hydrogen in its core and nuclear fusion will cease. With support against gravity suddenly gone, the core will collapse, heat up and reignite. Helium will be churned into carbon and oxygen as the sun's outer layers balloon outwards, transforming it into a red giant star.

Conclusion