The sun is the nearest star to the Earth, and without it, life could not exist on this planet. Though it looks relatively large in the sky, even though it is about 93 million miles away, the sheer magnitude of its size is usually not entirely grasped. Yet if all the other objects in the solar system; the Earth, the other planets, all the moons, all the asteroids, all the comets, and even all the dust, was all combined, it would still account for less than 3% of the solar system. The rest is contained in the sun. Over a hundred Earths would stretch across the disk of the sun, and the sun itself could hold over a million Earths!
The makeup of the sun is primarily hydrogen, the lightest element, with the other elements also being present. The energy of the sun comes from the nuclear conversion of hydrogen into helium, which is the second lightest element. When hydrogen atoms combine and merge to become helium, light and energy are released. The rate of this conversion means that hundreds of millions of tons of hydrogen are converted into helium every single second. Still, the sun is so huge that even though scientists estimate that it has been converting hydrogen into helium for almost 5,000,000,000 years, it is only halfway through its life!
There are some very interesting things that happen during this conversion process, not the least of which that a extreme temperature of over 25 million degrees Fahrenheit is generated. Almost as hard to grasp is that every time the conversion takes place, a particle of light is released. This particle, called a photon, then begins a very long journey to work it’s way all the way through the mass of the sun and into space. It will bounce around during this process, and it all means that it will take about a million years for it to actually escape from the sun. So the sunlight you may be enjoying as it streams through your window was actually generated over a million years ago!
The sun is also spinning on its axis, just as the Earth does. But there is a difference; the surface of the Earth has the same rotational speed. No so with the Sun. Since the sun is made of gas, it actually spins far faster at the equator than at the poles. So it takes about about 25 days for it to rotate at the equator while it takes about 11 days longer at the poles. At the same time, the core of the sun rotates at a speed somewhat between these two extreme. Over simplifying for a moment, this generates an intense magnetic field, far stronger than the one on the Earth. But because of the difference in rotational speed in different layers of the sun, the lines of force become twisted, and this becomes visible because of how it changes the way the hydrogen bubbles up. The result is that some areas on the surface of the sun become a few thousand degrees cooler than the rest of the sun. These appear as darker areas on the surface, though if we could look at them alone, they’d still be very bright. This is the cause of “sun spots”. There is growing evidence that the cycle of these sun spots have a greater impact on the climate on Earth than any other single thing, though scientist still don’t understand how.
The same process is what produces solar flares and prominences, or eruptions of solar matter enormous distances into space. These in turn create surges in the solar wind that constantly flows past the Earth. Such surges are responsible for the northern and southern lights, and if they are powerful enough, they can disrupt communications and electricity here on Earth.
So you see, understanding something about the sun is helpful for us here on Earth, in many different ways, far more than there is time to explain. I would hope that the reader explores the subject, and continues to learn more about the sun. Knowledge is a powerful ally. Learning about the facts we know about the sun is only the first step.
