Spectroscopy

How spectroscopy help scientists see elements in space

What is Spectroscopy?

Spectroscopy is the study of the properties of light that depend on wavelength. Spectroscopy was originated through the study of visible light dispersed according to its wavelength by a prism. Sir Isaac Newton was the first person to use a prism to disperse visible light into component colors and introduced the field of spectroscopy. The rainbow of colors Newton produced included all wavelengths of visible light and was later learned that two other spectra exist.

Types of Spectrum

Most light sources can be classified into three main types:


  • Continuous Spectrum: Produced by an incandescent solid, liquid, or gas under high pressure. The spectrum consists of an uninterrupted band of color. An example would be visible light generated by a common light bulb. This is the kind of spectrum Newton produced.


  • Absorption Spectrum: Produced when visible light is passed through a relatively cool gas under low pressure. The gas absorbs selected wavelengths of light so the spectrum appears continuous, but with a series of dark lines running through it.


  • Emission Spectrum: Produced by a hot gas under low pressure. It is a series of bright lines of particular wavelengths, depending on the gas that produces them.

Spectrum Pictures

So, how does spectroscopy help scientist identify elements in space?

Spectroscopy lets you take light and breaks it up into it wavelength components to make a spectrum. When this happens to light from outside in outer space, you will get a certain spectra. You may get some certain lines in the spectra which are absent (absorption spectra). You can figure out which elements can only absorb a specific frequency of light (related to its energy levels) therefore, the missing frequencies will tell you which element is shown. From this, you can find the elements in outer space.

Periodic Table of Elements

This website shows you the elements on the periodic table and which spectra they belong to. Practically all of them are emission spectra but it's nice to know which colors will show according to the element(s).