When the spectrum of light from the Sun is examined in high resolution in an experiment similar to that illustrated in Figure, dark lines are evident. These are called Fraunhofer lines, after the scientist who studied them extensively in the early nineteenth century. Altogether, about 25,000 lines have been identified in the solar spectrum between 2950 Å and 10,000 Å. The Fraunhofer lines are attributed to absorption of certain wavelengths of the Sun’s “white” light by gaseous elements in the Sun’s atmosphere.
▲ Figure Creating a spectrum. A continuous visible spectrum is produced when a narrow beam of white light is passed through a prism. The white light could be sunlight or light from an incandescent lamp.
(a) Describe the process that causes absorption of specific wavelengths of light from the solar spectrum. (b) To determine which Fraunhofer lines belong to a given element, say, neon, what experiments could a scientist conduct here on Earth?
Lesson 2 // Lectures 2 -The Celestial sphere is an imaginary sphere against which all celestial objects project -The Celestial equator is an imaginary extension of the Earth’s equator against the celestial sphere. This divides the celestial sphere into the north and south celestial hemispheres that both have poles just like Earth. -The horizon (our field of vision) only lets us see half of the celestial sphere at one time. -Stars appear to rise and set, from East to West, relative to the horizon. • The Diurnal path is the apparent path that stars take to go around the Earth. • The Ecliptic is the apparent path of the Sun. -Some stars never appear to rise or set and those are called circumpolar stars. What determines which stars we can see on any given night -