What’s Up With The Sun? A New Book — Guest Post by Pål Brekke

Pål Brekke as a new book about the orange orb of delight that hovers over us. Our Explosive Sun is a colorful introduction that would be good for newcomers or those of you who teach intro courses in astronomy or physics.

The Sun has fascinated me for many years. This is perhaps not so strange since I walked my first steps at the solar observatory at Harestua, just north of Oslo. My dad worked there then. During my studies at the University in Oslo my advisors inspired me to spend time doing public outreach. And so it was my interest for sharing knowledge about the mysteries of the Sun that led to my writing this book. Basically it is based on my public lecture series.

This book presents the properties of the Sun, how it has fascinated humans for thousands of years, and how it affects our technological society. My hope is that this book will inspire an increased interest in the Sun and for natural science in general. The Sun is a perfect entrance to natural science, since it affects the Earth and humans in so many ways. Solar physics interacts with many other scientific fields, such as physics, chemistry, biology, and meteorology to mention a few.

Needless to say the Sun is also an important part of natural climate variations. Even if the book do not include much details about this topic—it is of great importance to understand the climate system. In recent years there has been a growing concern about the possible anthropogenic forcing of climate change through the increasing atmospheric content of greenhouse gases. As a result the connection between solar variability and global climate change is sometimes considered a very controversial area of research. Whatever your stand is on this topic a good basic knowledge about the Sun is useful for all of us.

The Sun

The Sun provides energy to all life on Earth and drives the climate system and is therefore very important to all of us. It powers photosynthesis in plants and is the ultimate source of all food and fossil fuel. However, storms on the Sun can also interfere with systems on Earth that our society depends upon.

Looking at the sky with the naked eye, the Sun seems static, placid, and constant. From ground the only noticeable variation in the Sun are its location (where it will rise and set today?). But the Sun gives us more than just a steady stream of warmth and light.

Situated 150 million kilometer way from us the Sun is a huge thermonuclear reactor, fusing hydrogen atoms into helium and producing million degree temperatures and intense magnetic fields. Near the surface, the Sun is like a pot of boiling water, with bubbles of hot electrified gas. The steady stream of particles blowing away from the Sun is known as the solar wind. Blustering at 1.5 million kilometer per hour the solar wind carries a million tons of matter into space every second (that’s the mass of Utah’s Great Salt Lake).

Every 11 year the Sun undergoes a period of activity called the “solar maximum”, followed about 5 years later by a period of quiet called the “solar minimum”. During solar maximum there are many sunspots, and during solar minimum there are few. Thus, one way of tracking solar activity is by observing the number of sunspots. Sunspots are dark patches like freckles on the solar surface formed when magnetic field lines just below the Sun’s surface are twisted and poke through the solar surface. Sunspots can last from a few hours to several months, and a large sunspot can grow to several times the size of Earth. Though the Chinese recorded some observations as early as 28 B.C., scientists have been observing and recording sunspots since about 1610 when Galileo Galilei pointed his telescope towards the Sun.

Why do scientist care about Sunspots? Because they are visible signs of the turmoil inside the Sun that lead to space weather effects on Earth. Coronal mass ejections (CMEs) and solar flares are often associated with sunspot groups.

Over the next few years more solar storms will occur as the Sun approaches maximum activity in 2013. Thus, we will experience more northern lights at mid- latitudes. Solar storms and space weather affect our technology-based society. We are becoming more and more dependent on space-based technology like satellites, GPS navigation, radio communication and power grids, which are vulnerable to space weather effects.

The new book Our Explosive Sun: A Visual Feast of Our Source of Light and Life provides a detailed introduction to the dynamics of the Sun and how it affects Earth. The book examines the many ways that the Sun impacts our world, including the beautiful northern and southern lights, and how greatly the Sun affects our technology-based society.

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Pål Brekke is a Norwegian solar physicist with a doctorate from the University of Oslo in astrophysics and is now a senior advisor for the Norwegian Space Centre. He has worked with state-of-the-art space-based solar telescopes since 1985 and has published over 40 peer-reviewed articles, 70 proceeding papers, and more than 30 popular science articles. For six years he was the ESA Deputy Project Scientist for the SOHO spacecraft.