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During this course you will be introduced to the mathematical equations that can be used to model a wide variety of different solar phenomena. It is a mathematical course and no prior knowledge of astronomy, electromagnetism or fluid mechanics will be assumed. The observational side of solar physics will be exhibited by pictures, films and through this hypercard stack. Thus, many solar phenomena will be illustrated and, then, simple mathematical models that describe them will be presented.
Since the early 1970's there has been a major change in our understanding of the physics of the Sun. This has been brought about by the tremendous advances in observations with a series of satellite mission that have supplemented our ground-based telescopes. From the ground we can observe the Sun in white light and a variety of different wavelengths, including radio. However, the Earth's atmosphere acts as a filter that eliminates large sections of the electromagnetic spectrum. In particular, X-rays from the Sun are invisible at ground level and it was only with the advent of space missions that we began to see the Sun in its complete glory.
The Skylab mission showed us that the Sun emits radiation in the soft X-ray wavelengths and indicated that the outer layers of the Sun are extremely hot with temperature of several million degrees Kelvin. This came as a surprise since the optical telescopes tell us that the surface of the Sun is at a few thousand degrees Kelvin. Major space missions have since followed namely Solar Maximum Mission (SMM) in the late 1970's and early 1980's. In fact, SMM was the first satellite to be rescued by the Space Shuttle. More recently, the Japanese satellite Yohkoh, meaning sunbeam, has added to our knowledge by studying the Sun in higher and higher resolution (or more simply detail). The Ulysses mission was the first satellite to leave the ecliptic plane and travel over the poles of the Sun. Ulysses used the gravity of Jupiter to sling it out of the plane of the planets in the first maveovre of its kind. The next major solar mission is called SOHO, (Solar and Heliospheric Observatory) and it will be launched in October 1995.
The result of all this new information has been a complete rethinking of a lot of long cherished beliefs and it is the job of the solar theorist to explain these interesting observations. We are succeeding and it is an exciting time to be working on these problems.
The theory depends upon two disciplines, namely electromagnetism and fluid mechanics, into the topic of Magnetohydrodynamics (or more simply MHD). MHD only really developed in the 1930's but only slowly until the late 1950's and early 1960's when it was realised that MHD gave a good description of plasmas in the cosmos as well as the Sun and other stars. It is now appreciated that the Sun can act as a laboratory, illustrating astrophysical MHD, since there is no laboratory on the Earth that can look at a plasma under the same physical conditions.
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