The colors are artificial, changing from yellow to white to blue with increasing energy of the X-rays. (b) X-rays: here, the view emphasizes the point-like X-ray sources nearby. (a) Visible light: this shows part of the Orion region as the human eye sees it, with dotted lines added to show the figure of the mythical hunter, Orion. The same part of the sky looks different when observed with instruments that are sensitive to different bands of the spectrum. Third, we need some type of detector, a device that senses the radiation in the wavelength regions we have chosen and permanently records the observations.įigure 6.2 Orion Region at Different Wavelengths. But at other times, we want to see individual spectral lines to determine what an object is made of, or to measure its speed (as explained in the Radiation and Spectra chapter). For example, we might simply want to separate blue light from red light so that we can determine the temperature of a star. Second, there is an instrument attached to the telescope that sorts the incoming radiation by wavelength. Just as you can catch more rain with a garbage can than with a coffee cup, large telescopes gather much more light than your eye can. First, there is a telescope, which serves as a “bucket” for collecting visible light (or radiation at other wavelengths, as shown in ( Figure 6.2). There are three basic components of a modern system for measuring radiation from astronomical sources. Describe the two basic types of visible-light telescopes and how they form images.Describe the main functions of a telescope.Describe the three basic components of a modern system for measuring astronomical sources. By the end of this section, you will be able to:
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