New eyes on our universe… What can we “spectra”to learn next?
EMSwaves are continuous and range from very long, slow waves like radio waves that can be as large as thousands of kilometers in length to short, fast waves like gamma rays that can be smaller in length than the size of an atom. • Humans can only see the medium length waves of visible light, but we can use other wavelengths.
What is a Spectroscope? • A spectroscope is used to identify elements by the colors they give off. • Every substance gives off light when it becomes hot enough and every element has its own special color. • A spectroscope separates the light into colored lines called spectra. It is like an element’s fingerprint. No two elements have the same spectrum, but the same element always has the same spectrum!
The most important part of a spectroscope is a prism. It breaks up white light into bands of color.
There are 92 natural elements. • 67 of these elements can be found in our star, the sun. • Each element’s spectrum has specific bands of lines that stand for different wavelengths. These bands may look like dark lines where the color has been absorbed at a particular wavelength.
Absorption Spectra • Star spectrums are collected by telescopes from outside our atmosphere and therefore are always seen and studied as dark line spectrums or “absorption” spectrums. • Absorption spectrums are NEVER viewable from the Earth. We see “continuous” spectrums because of all of the light pollution.
Bright Line Spectra • A “bright line” spectrum may be seen where energy is added to an element. Bright lines of color can then be seen at the different wavelengths for a particular element. • This is the type of spectra you will see in the lab.
Energy wavelengths and Stars • Most stars emit energy in all wavelengths, but how much of each wavelength depends on their temperature. • Younger, hotter stars emit shorter waves with higher energy. • Cool stars emit mostly cooler stars with lower energy. • Our Sun is a medium star so it mostly emits medium wavelengths in “visible” light. This is why our eyes were made to see in this light range.
A continuous spectrum is, as the name implies, a parade of all the colors from the deepest red to the ultraviolet - of which the rainbow in the sky is a good example. In the laboratory a continuous spectrum can be produced by heating a solid, a liquid, or an opaque gas to a fairly high temperature - several thousand degrees Fahrenheit. Light from the electric lamp filament, for example, produces such a spectrum. Continuous Spectrum When light emitted by a gas through which an electrical discharge is passing produces a spectrum consisting of a few isolated parallel lines, it is known as a "bright line spectrum" or "emission spectrum". ) .
Dark line spectrum (or absoption spectrum) is due to absorption of light of particular wave length by relatively cool gases. The wave lengths absorbed are identical to the wave lengths that the gas would emit when properly excited.
What can we learn from using a spectroscope? • The chemical make up of our sun and other stars/how old a star is… • The make up of the atmosphere of planets (and moons?) • How fast a heavenly body is moving • In what direction a body is moving • How hot a star is • If a body is rotating and in what direction • Magnetic fields???