Editing Visible spectrum (section)

==Spectroscopy==
[[File:Atmospheric electromagnetic opacity.svg|thumb|upright=1.95|[[Earth's atmosphere]] partially or totally [[Opacity (optics)|blocks]] some wavelengths of electromagnetic radiation, but in visible light it is mostly transparent]]
{{main|Spectroscopy}}

[[Spectroscopy]] is the study of objects based on the spectrum of color they emit, absorb or reflect. Visible-light spectroscopy is an important tool in [[astronomy]] (as is [[Astronomical spectroscopy|spectroscopy]] at other wavelengths), where scientists use it to analyze the properties of distant objects. [[Chemical element]]s and small [[molecule]]s can be detected in astronomical objects by observing [[emission line]]s and [[absorption line]]s. For example, [[helium]] was first detected by analysis of the spectrum of the [[Sun]]. The shift in frequency of spectral lines is used to measure the [[Doppler shift]] ([[redshift]] or [[blueshift]]) of distant objects to determine their velocities towards or away from the observer. [[Astronomical spectroscopy]] uses high-dispersion [[diffraction grating]]s to observe spectra at very high spectral resolutions.
{{clear}}