What is the importance of the Sun's production of energy? How could we use it to our advantage?

We completed research on the Sun, its structure, weather events, how it produces energy (fusion), and space missions conducted by various agencies throughout the world. We also completed research on fusion, how it works, the development of fusion reactors, and the difference between fission and fusion.

1. The Sun

The Sun is our solar system’s powerhouse, its name deriving from the Latin word "Sol". Without it, life on Earth is not possible. It produces approximately 44 quadrillion watts of energy annually. Of that, about 342 watts per square metre of energy falls onto Earth. The Sun is one of the billions of stars found in the Milky Way, being around 4.5 billion years old. It is classified as a G2 V yellow dwarf star and is composed of hot, glowing hydrogen and helium. It is the centre of our solar system, the very thing that holds it together. Without the Sun's gravity, our solar system would collapse.

About 4.6 million years ago, a nebula collapsed under its own gravity, turning into a spinning cloud of gas and dust. The mass began to spin faster and faster until it flattened into a disk. Much of the nebula's material was used to form the Sun, while the remaining material formed the planets and other objects that orbit the Sun. The leftover gas that was not used to form anything was blown away by the solar winds created by the Sun. The Sun's spin has a tilt of 7.25 degrees, with different parts of the star rating at different rates because it is not solid. At the equator, it takes the Sun about 25 Earth days to spin around, but about 36 Earth days to do the same at the poles. The Sun is surrounded by several dust rings, which would have been a disk of gas and dust in the early days of the solar system when it was still forming.

Like most stars, the Sun does not have a surface, being primarily made up of hot gases like hydrogen and helium. It is called a main sequence star, due to it steadily undergoing hydrogen fusion. It is the easiest study for us to study due to its close proximity, and is unusually calm for its size and class.

1.1 Structure

Located about 150 million kilometres (93.2 million miles) from Earth, the Sun is roughly 100 times wider than the Earth, having a diameter of approximately 1.4 million kilometres (0.87 million miles). It is so immense that it would take over 330,000 Earths to match its mass, and about 1.3 million Earths to match its volume. While it accounts for 99.8% of the entire solar system's mass, the Sun is still not the largest star. Some, up to 100 times the Sun's exist throughout our galaxy. The Sun, a ball of hydrogen and helium, is held together by its gravity and is composed of several different regions.

The core is the hottest part of the Sun, with temperatures can reach up to 15 millionº Celsius (27 millionº Fahrenheit) in this region. Nuclear reactions occur in this region, where hydrogen fuses to form helium. The energy produced by the core is carried out to other regions through radiation. It has a density of 150 grams per square centimetre, which is approximately eight times the density of gold, and 13 times that of lead. The radiative zone surrounds the core and extends outward to about 70% of the Sun's radius. In this zone, energy travels slowly in the form of radiation. Energy travelling through this zone takes about 170,000 years to reach the convection zone. The convection zone carries out bubbles of plasma towards the surface. Here, temperatures drop to around 2 millionº Celsius (3.6 millionº Fahrenheit). The motion of the plasma in the zone creates magnetic fields and Sunspots on the surface of the Sun. In the photosphere, meaning "light sphere", temperatures drop even further to about 5 500º Celsius (9900º Fahrenheit), still hot enough to make carbon boil. It is the surface of the Sun, emitting the most visible light. The photosphere is the part of the Sun that can be viewed with our own eyes here on Earth. It is about 402 kilometres (250 miles) thick and is the first layer of the solar atmosphere. Most of the Sun's radiation escapes outward from the photosphere into the rest of space. Above the photosphere, the chromosphere is a thin layer that is the fine red rim seen around the Sun during solar eclipses. The transition zone is the layer where the chromosphere rapidly heats, and becomes the corona. The corona forms the Sun's upper atmosphere. It is the white crown of streaming plasma seen during solar eclipses along with the chromosphere, shaped by the Sun's magnetic field.

1.2 Magnetic Field

The Sun generates magnetic fields that extend out to space, forming the interplanetary magnetic field. It is carried throughout the solar system by solar wind, streams of electrically charged gas, blowing outward in all directions. The rotating spiral spun out by the magnetic field is known as the Parker Spiral)

1.3 Solar Cycles

A solar cycle is when the Sun's poles change magnetic polarity, meaning its north and south poles swap, each cycle lasting about 11 Earth years. During this time, the photosphere, chromosphere, and corona become violently active, a change from their usually quiet and calm behaviour. During the solar maximum, solar flares, Sunspots, and coronal mass ejections are quite common. The last solar maximum occurred in December 2019, marking the start of the twenty-fifth solar cycle. Experts co-sponsored by NASA (National Aeronautics and Space Administration) and NOAA (National Oceanic and Atmospheric Administration) predict that the Sun's activity will begin to ramp up in July of 2025.

Solar activity can release massive amounts of energy in particles, with these changes affecting the weather on Earth. The strongest recorded magnetic storm was the Carrington Event, named after British Astronomer Richard Carrington who observed the solar flare. The flare occurred on September 1, 1859. It caused telegraph systems to haywire, shocking operators with spark discharges, and also setting the telegraph paper on fire. The skies erupted into red, green, and purple auroras that allowed newspapers to be read as though it were daylight. Occurring just before dawn, the auroras were visible as far south as Cuba, the Bahamas, Jamaica, El Salvador, and Hawaii. Another solar flare on March 13, 1989, plunged 6 million people into darkness for hours. It disrupted power transmitting from the Hydro Québec station in Canada, and also caused power surges in New Jersey, US, melting transformers.

1.3.1 Sunspots

Sunspots are dark blotches that appear on the surface of the Sun. They appear, grow in number, and diminish, changing as the Sun's magnetic field changes. They are somewhat cooler and less luminous than their surroundings. They are temporary, fluctuating in number over the 11-year solar cycle.

1.3.2 Coronal Mass Ejections

Coronal mass ejections are powerful eruptions that occur on the Sun's surface, releasing billions of tons of material into space. If they hit Earth, they could cause fluctuations in the magnetic field, and in turn, damage infrastructure. They could damage electricity flow or related infrastructure, satellites, take down entire power grids, disrupt communications, and also endanger astronauts currently in space.

1.4 Solar Winds

Solar winds are responsible for carrying out the Sun's magnetic field from the centre of the solar system towards the outer regions, forming the extended atmosphere of the Sun. Materials that leave the corona at supersonic speeds become solar winds. Referred to as the heliosphere, it forms a magnetic bubble around the Sun and extends beyond the orbit of the planets in the solar system. All planets, including Earth, exist within the heliosphere. Outside, is interstellar space. The winds are what cause comets to develop ion tails, bluish trails that you see on comets. They are also responsible for creating the auroras seen from Earth.

1.5 Space Missions

Various space missions have been sent by many agencies since the beginning of the Space race. These missions include HELIOS 1, Ulysses, the Voyager probes, STEREO, SDO, SOHO, the Parker Solar Probe, and the Solar Orbiter Mission.

1.5.1 HELIOS 1

A joint venture between NASA and DLR (German Aerospace Center) first beginning in 1974, HELIOS 1 was the first probe dedicated to orbiting and studying the Sun. While Luna 1 was technically the first, it was an accident. The probe made a variety of measurements of the environments around the Sun, including solar winds.

1.5.2 Ulysses

Ulysses was a joint venture between NASA and ESA (European Space Agency), being the first spacecraft to survey space around the Sun''s poles. It used Jupiter's gravity as a slingshot and was able to travel around the Sun at a steeper angle than the planet's orbits. It showed that the Sun's magnetic field is carried out in more complex waves than was previously expected by researchers and scientists and that the magnetic fields around the poles were weaker than was thought to be.

1.5.3 Voyager Probes

The Voyager probes reached interstellar space in 2012 and 2018 respectively,  the only human-made objects to travel to and enter interstellar space. Both probes transmitted data back to JPL (Jet Propulsion Laboratory). Voyager 2 launched in August of 1977 and was followed by Voyager 1 in September of 1977. The two probes are the most distant human-made objects from Earth, with Voyager 1 being about 25 billion kilometres (15 billion miles) away, and Voyager 2 being over 21 billion kilometres (13 billion miles) away.

1.5.4 STEREO

STEREO (Solar TErrestrial RElations Observatory) are twin spacecraft in NASA's Solar Terrestrial Probes program. The two spacecraft were set to study the structure and evolution of solar storms emerging from the Sun and moving out towards outer regions of space. The spacecraft provided the first 3D view of the Sun's surface, capturing data about extreme solar storms and other activities occurring on or near the Sun. While contact was lost with STEREO B in 2016, STEREO-A is still operational.

1.5.5 SDO

SDO (Solar Dynamics Observatory) was launched in 2010 and monitors the Sun at different wavelengths. Using data captured by SDO, scientists were able to predict seven of the nine largest solar flares in the last solar cycle.

1.5.6 SOHO

SOHO (Solar and Heliospheric Observatory) has been observing the Sun for over 25 years from Lagrange point 1, a region of space between Earth and the Sun where both gravities balance, making orbits more stable. It virtually creates solar eclipses on demand through coronagraphs that block Sunlight, allowing for the view of the corona and tracking of solar eruptions.

1.5.7 Parker Solar Probe

Launched in 2018, its trajectory aimed for some of the most extreme conditions in space. It uses Venus' gravity to slow down and get closer to the Sun and aims to study the star from within the corona.

1.5.8 Solar Orbiter Mission

Led by ESA and launched in 2020, the mission will take the first-ever close-up images of the Sun's polar regions. It will also measure the properties of solar wind particles and allow scientists to trace the particles down to where they originated from on the Sun's surface. It will also create detailed maps of the Sun's magnetic field on, as well as below the surface of the Sun. This mission, along with the Parker Solar Probe aims to solve why the corona is so much hotter than its surface. It is suspected that the heating of the corona may be tied to the magnetic field.

1.6 Stellar Neighbours

The Sun's nearest stellar neighbour is the Alpha Centauri triple star system, made up of red dwarf star Proxima Centauri, and Alpha Centauri A and B. Proxima Centauri is 4.24 light years away, and Alpha Centauri A and B are 4.37 light years away. One light year equates to about 9.5 trillion kilometres (5.9 trillion miles).

1.7 Energy

Eventually, the Sun will run out of energy. It will slowly expand into a red giant star when it begins to die. Currently, scientists predict that the Sun is slightly under halfway through its lifetime. In about 5 billion years, the star will run out of hydrogen and begin to transition into a red giant star. The solar atmosphere will eventually cool. Nearby planets like Mercury, Venus, and possibly Earth will be engulfed, while outer planets will survive. Planets like Jupiter and Saturn might become warm enough to have water and be able to sustain life. In about 8 billion years, the Sun will completely run out of fusion materials, and collapse into a white dwarf star. Outer planets like the gas giants would survive the dimming of the star but would be cold and dark.

2. Fusion

Fusion is what is used to power the Sun and other stars. It occurs when two light nuclei merge to form a single heavier nucleus. During this process, energy is released due to the total mass of the resulting nucleus being less than the mass of the two original nuclei; the leftover mass becomes energy.

Fusion takes place in plasma, one of the four fundamental states of matter. The hot charge of gas is made up of positive ions and free-moving electrons, each containing unique properties. For fusion to occur, the nuclei must collide with each other at extremely high temperatures, about 10 millionº Celsius (18 million Fahrenheit). This temperature is easily reached in the Sun's core, allowing for fusion. The high temperatures provide the nuclei with enough energy to overcome their mutual electrical repulsion, and once they come into close range of each other, their attractive force outweighs the repulsion and allows for fusion. The nuclei must be confined in a small space to increase the chances of collision, where the Sun's extreme pressure creates the conditions to allow for fusion.

2.1 Fusion Reactors

The possibility of creating fusion reactors has been a quest of many scientists and engineers. If fusion can be replicated on Earth, it could virtually provide a clean, safe, limitless, and affordable source of energy that easily meets the world's growing demand. Fusion would be able to generate four times more energy per kilogram of fuel compared to fusion, equating to nearly 4 million times more energy than burning oil.

Most early reactor concepts use a mixture of deuterium and tritium, which are hydrogen atoms that contain extra neutrons. The materials needed for fusion could easily and cheaply be obtained, with deuterium being able to be extracted from seawater, and tritium potentially being able to be produced from the reaction of fusion-generated neutrons with lithium. It does not emit greenhouse gases like carbon dioxide and could provide a clean source of energy that could power the world's needs as energy demand continues to rise in our developing world. However, for fusion to take place on Earth, temperatures of over 100 millionº Celsius (180 millionº Fahrenheit) are required for deuterium and tritium to fuse. With temperatures near that of what is required, fusion on Earth may be able to be achieved soon as research continues to be carried out in over 50 countries. 

2.2 Drawbacks

While some may say fusion is the future of all energy production, it too, like all other energy sources, has drawbacks. Neutron radiation is one of the biggest issues with prototype fusion reactors right now. Radiation can travel centimetres out into the structure, damaging the reactor's materials. Extreme temperatures of 100 million° Celsius are also required to create the conditions for fusion. While deuterium can be extracted from seawater, tritium is radioactive and must be generated using lithium. Losses in tritium, even those as small as 1%, could result in the reactors being unable to sustain themselves without support from fission reactors. If fission reactors are needed to sustain the fusion reactors, this could complicate things more. In addition to the issues with tritium losses, the reactors would consume back up to 20% of the energy they produce due to heating, cooling, and other structures required in reactors. With this, comes high operating costs. Component replacements would result in expensive repairs and long downtimes with reactors. Fusion reactors would also require over double what fission reactors do. These issues with manufacturing self-sustaining fusion reactors aren't the only problem though, working with fusion has the potential to convert uranium-238 into weapons-grade plutonium-239. If it falls into the wrong hands, there could be catastrophic results for the entire world.

2.3 Fission vs Fusion

While fission and fusion are both nuclear processes that release energy by altering nuclei, fusion involves the combining of nuclei, while fission involves the splitting of nuclei. Fusion is the combining of two light nuclei, the process used by the Sun and other stars to power themselves. In contrast, fission splits a heavy nucleus into two smaller nuclei, releasing energy in the process. Fission has been in use since 1942, but generates a great amount of radioactive waste. Fusion, while still in a developmental state, has the potential to provide a cleaner output, along with more energy, than fission.

 

No data was collected for this research project.

In conclusion, the Sun is key to life on Earth, holding our solar system in fragile balance. Events that occur on the sun, especially strong solar activity, can directly affect us here on Earth. These events can take out power grids, disrupt satellites and communications, and even create the beautiful auroras we see in the skies. As seen by past events, the relationship between the Sun and the Earth is deeply intertwined; what happens on the star can also change how things happen on Earth. Every single second, the Sun produces hundreds of thousands of times more energy than we use here on Earth in a year. It is a powerhouse of energy, and if harnessed, could power the Earth for millions of years. Our star uses fusion to create its energy, like other stars. This is different from fission. Though both are nuclear processes used to produce energy, fusion is the opposite of fission. Fission involves the splitting of nuclei, while fusion involves the combining of two. Fission has been in use for well over half a century, and is a leading source of renewable energy that does not produce greenhouse gases like carbon dioxide. However, like all energy sources, it produces a problematic amount of nuclear waste.

While fusion is said to produce less, it is not the solution to our energy needs some may draw it out to be. It is still years, even decades, away from commercialization. It is far from being a usable product, and requires many, many more years of research, development, and funding for it to be a viable option in energy production. The break-even point may have been achieved, but scientists still have yet to reach the ignition point. In the current state, there is no way for fusion reactors to sustain themselves, with more energy going out than in. Even if scientists and engineers can achieve the ignition point, we may still face issues with commercialization. Due to its expected high maintenance and runtime costs, few companies may be willing to take up the responsibility of building, maintaining, and licensing reactors for our use. Fusion reactors would require over double the amount of employees all working to maintain a reactor, as well as require expensive component replacements due to damage and erosion from radiation and plasma. Many may also be unwilling to deal with long downtimes if a reactor were to require repairs, disrupting energy production, and, in turn, profits.

In today's world, we may not yet be ready for the future of renewable energy production like fusion reactors. This may be feasible in years to come, but it is unlikely to happen in the foreseeable future. With more research and funding into development, there may be a way to harness the Sun's power, but as of now, fission reactors seem to be the way to go. Along with the use of other renewable energy sources like wind, solar, hydro, geothermal, and biomass power, our world is already shifting away from greenhouse gas-emitting sources like coal and fossil fuels. While all of these power-generating sources have their drawbacks, they seem the easiest to implement and afford, especially for undeveloped or developing countries. Building giant fusion or even fission reactors requires high upfront costs, along with high maintenance and repair costs too in the long run. Other renewable energy sources like solar or wind power are simply cheaper, lower maintenance, and a far more appealing option for many. Solar power is also growing in popularity among many, as they are cost-effective, relatively cheap, and easy to install and maintain. Some governments are even offering subsidies for those who want to install panels on their rooftops as a step towards clean, renewable energy. Renewable energy seems to be the future in our world, but most are looking for easier and cheaper options that have already been implemented across the world.

Nuclear reactors like fusion and fission reactors are extremely efficient but just don't have the same appeal as other renewable sources. Since nuclear energy is still a relatively new thing, some are afraid of what it could create. It has already been seen from the creation of nuclear weapons that investing in the development of it could very well cause the discovery and creation of nuclear weapons, even stronger than the atomic bombs developed by the Manhattan Project in 1945. If an all-out war were to break out with these weapons in the arsenal of many countries, it could directly lead to the end of the human race, possibly even the world. People are afraid, and rightfully so. Perhaps, when there is a time that we can achieve peace and trusting communications between powers, the development of nuclear power could be furthered without great risks of war and danger, and fusion reactors could be the main player in energy production. However, with the current state of the world, this may be far from the present day. 

 

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Header image by by Jessie Eastland. Source: https://en.wikipedia.org/wiki/Sunset

Cover image by NASA / Johns Hopkins APL / Ben Smith. Source: https://skyandtelescope.org/astronomy-news/humanity-has-touched-the-sun/

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