Researchers are learning that variations in the solar wind flow can cause dramatic changes in the shape of the Earth's magnetic field, which can damage satellites and disrupt communications and electrical power systems. The nature and origin of the solar wind is one of the main mysteries ESA's solar observatory SOHO was designed to solve. Just below the surface of the Sun there are large convection cells, and each cell has a magnetic field associated with it. Identification of the detailed structure of the source region of the fast solar wind is an important step in solving the solar wind acceleration problem. A spectrum results from the separation of light into its component colours, which correspond to different wavelengths.
Blue light has a shorter wavelength and is more energetic than red.
A spectrum is similar to what is seen when a prism separates white light into a rainbow of distinct colours. By analysing light this way, astronomers learn a great deal about the object emitting the light, such as its temperature, chemical composition, and motion. The hot gas in the solar wind source region emits light at certain ultraviolet wavelengths. When the hot gas flows towards Earth, as it does in the solar wind, the wavelengths of the ultraviolet light emitted become shorter, a phenomenon called Doppler shift. This is similar to the way an ambulance siren appears to change tone as it speeds by.