The Spectroscope

What is it? A spectroscope is a tool used by astronomers to separate light into its rainbow of colors in the spectrum. This technique used to help scientists determine the composition of objects made up of hot incandescent gases (like stars) and cool gases (like planetary atmospheres).  Spectrometers are used to analyze the amounts and types of spectral light that comes from objects in space. 

Spectroscopes break down the light emitted or absorbed by chemical elements into specific lines of color.  Every chemical element has a "fingerprint" of its own that can be used to identify it.  These fingerprints are generally produced when electrons change orbital levels as they gain or lose energy.  That’s cool Different energies produce different colored lines.

Star Fingerprints Every chemical element on the periodic table has its own spectral fingerprint that identifies it.  (this is important) When looking at spectra from objects like stars and planetary atmospheres, it is easy to identify the chemical elements present by matching the colored spectral lines with the elements spectral fingerprint. See Spectra of gas discharge

Wavelengths Look at the chart on the right – notice the different areas of the scale for each wavelength. Where do you find: Radio waves? Microwaves? Infrared Visible light Ultraviolet X-rays Gamma rays

What is the Electromagnetic Spectrum?

Types of Spectra Continuous spectrum – unbroken rainbow of color. What order do the colors go in?

Bright line spectrum Un evenly spaced lines of different colors which are unique to each element.

Different types of spectrum analysis

Element discharge samples http://jersey.uoregon.edu/elements/Elements .html

Spectroscope lab Let’s see how it works with some samples of isolated gases

What is the doppler effect? A change in wavelength of light or sound from moving objects ie: a train passing What happens as the train is moving closer? Moving away? Doppler effect animations

Doppler shift With stars in a spectrum there is also doppler effect. We can see it through the spectroscope signatures, and notice whether there is a red or blue shift

Red Shift or Blue ? In red shift- stars are moving away from Earth, so the visible spectrum shifts more toward the red end, Blue Shift – stars are moving closer toward the earth