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Solar Coordinate Systems
In solar observation and imaging, coordinate systems are used to identify and communicate locations on and around the Sun. The Sun is made of Plasma (physics), plasma, so there are no permanent demarcated points that can be referenced. Background The Sun is a rotating sphere of Plasma (physics), plasma at the center of the Solar System. It lacks a solid or liquid surface, so the interface separating its interior and its exterior is usually defined as the boundary where plasma becomes opaque to visible light, the photosphere. Since plasma is gaseous in nature, this surface has no permanent demarcated points that can be used for reference. Furthermore, its rate of rotation varies with latitude, rotating faster at the equator than at the Poles of astronomical bodies, poles. Cardinal directions In observations of the solar disk, cardinal directions are typically defined so that the Sun's northern and southern hemispheres point toward Earth's northern and southern celestial poles, r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar Observation
Solar observation is the scientific endeavor of studying the Sun and its behavior and relation to the Earth and the remainder of the Solar System. Deliberate solar observation began thousands of years ago. That initial era of direct observation gave way to telescopes in the 1600s followed by satellites in the twentieth century. Prehistory Stratigraphy, Stratigraphic data suggest that solar cycles have occurred for hundreds of millions of years, if not longer; measuring varves in precambrian sedimentary rock has revealed repeating peaks in layer thickness corresponding to the cycle. It is possible that the early atmosphere on Earth was more sensitive to solar irradiation than today, so that greater glacial melting (and thicker sediment deposits) could have occurred during years with greater sunspot activity. This would presume annual layering; however, alternative explanations (diurnal) have also been proposed. Analysis of tree rings revealed a detailed picture of past solar cycle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
