Learn more about how the sun works and the importance of studying the sun.
Read the full transcript »

Although we are investigating the planets of our solar system, we have also been trying to understand more about our sun. Man has been fascinated by the sun since the beginning of time. In ancient Britain, the druids built a mysterious monument to it while in Egypt. The sun was worshipped as a deity and its passage from day to night was sanctified. The Mayans offered sacrifices to the sun, the Aztecs offered sacrifices to the sun. The Aztecs found it represented time. Although there have been many representations of it from paintings to monuments, we still have a long way to go to fully understand its workings. In the early years of man’s study of the universe, there were different beliefs as to its role. Some thought it was not the center of the solar system, but that the earth was. It was Claudius Ptolemy who devised the first complete system of the universe. He lived in Alexandria around 200 A.D. and said that the earth was the center of the universe. The sun and the planets turned around it in circles. Beyond the planets lies the celestial sphere of stars which also turns around the earth. We have learned much since those times. Today we know that the family of planets, asteroids and comets circle the sun. We also know that our star is like a tiny grain of dust in the universe. In fact there are so many stars, we cannot count them all. Our sun is an average size star. It has been found that some small stars do not travel in the company of other stars and our sun is one of these. Astronomers are able to study the sun in great detail to try and get a better understanding of its structure and energy. It is almost like a vast laboratory. The sun could be studied using a spectroscope. The dark lines that cut across the spectrum band are produced by the radiation from the sun’s interior, shining through its atmosphere. Each line is the signature of a chemical element such as sodium, iron and calcium. It is this array of lines that forms the code which describes the properties and motion of the star. By narrowing the view of the sun to a single line at the spectrum, each level of the solar atmosphere can be photographed. By using computer mapping and color processing, it is possible to distinguish the levels of brightness. In this way, a detailed and multi-dimensional picture is obtained of the sun undergoing dramatic and turbulent change. The sun is a sphere of hot seething gases and surges of radiation. Most of the lines we get from the sun comes from a thin, bright layer which defines its visible edge, the photosphere. Above it, the chromosphere, a region of flaming outbursts of gas extends through a transition zone to the thin, outer atmosphere of the corona. Deep beneath the sun’s atmospheric shell is the core, a violent, nuclear furnace. Here, hydrogen is fused into helium and in the process, some of the matter is converted into an enormous amount of energy. Radiating outward is a gas, it behaves like a boiling liquid beneath the surface. The turbulent, bubbling motion is visible in the granular cells of the phonosphere. Sun spots, regions of intense magnetic fields appear on the surface. They disappear in a few hours or grow and persist for months in a mysterious 11-year cycle. The sun rotates once every 27 days. Because its equatorial regions rotate faster than the polar caps, the shearing action and the gas contorts the magnetic field into tangled structures, which gives rise to the sun’s eruptive action. The dark areas across the solar disc are holes which may provide new clues to the sun’s interior and may be a source of the solar wind, which blows outwards to the farthest planets. On earth, the effects of the solar events are visible when auroras light up the dark, arctic sky and radio communication is disrupted. The sun is an average, middle-aged star, yet it will generate heat and light for billions of years to come, as it has for five billion years past. It dominates the motion of all bodies in the solar system.

Advertisement
Advertisement
Advertisement