Optical wavelengths are very tiny, and a unit called the Angstrom is often used. At wavelengths longer than optical light, the Angstrom unit becomes increasingly awkward. At 10,000 Angstroms, astronomers usually convert over to another unit called a micron, which is one-millionth of a meter. This seems to be the unit of choice for the infrared. For historical reasons, radio astronomers often refer to the frequency of radio light instead of the wavelength.
Most wavelengths used in astronomy are in the MHz and GHz range.
In these regions, it is conventional to show the spectra on a scale in energy units instead of wavelengths. Click here to go to next section. Return to Spectroscopy Home Page.