SPECTRUM & UNIVERSE
We know that just by studying the
SPECTRUM an astronomer can
tell you what a star billions of miles away is made of and the elements present , take the star temperature, figure out how fast it is moving, and whether the motion towards the Earth or away from it.
The spectrum consists of the
lines into which white light is broken up when it is bent, as when it goes through a prism . All across the spectrum, in addition to the shadings of color, there are hundreds of parallel lines . They are know as Fraunhofer lines, in honor of their discoverer.
Each chemical
element in a gaseous or vapor state has its own pattern of lines occupying its own place in the spectrum. The lines stand for the colors taken up from the light by the element when it heated so that it glows. This means that a scientists can find out what materials are present in any substance , no matter how far removed. Each element makes its own “dark line” or absorption spectrum, different from those of any other element. By simply comparing the spectrum of a material being studied with spectra of elements known in the laboratory, the physicist can tell what it is. In other words, each element leaves its fingerprint in light patterns.
Since the
temperature causes an element line positions to change in the spectrum, astronomers can tell a great deal about the temperature of stars billions of miles away. When a star is moving towards us , lines in the spectrum are shifted toward the violet end of the spectrum . When a star is moving away, the lines are shifted toward the red end of the band. From the amount of shift or displacement, scientists calculate that some stars are hurtling through space at the rate of 150 miles per second.
Though it looks simple as a laboratory experiment in practice it involves a lot of money and sophisticated instruments and precise calculations with near accurate results involving high tech computers. But for the layman the above information is enough as a General Knowledge.
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