page_title: Zeeman effect
section_title: Astrophysics
hierarchical_section_title: Zeeman effect / Applications / Astrophysics
caption_attribution_description: English: Magnetic field of sunspot (left) splits absorption line according to Zeeman effect (right).
context_page_description: The Zeeman effect, named after Dutch physicist Pieter Zeeman, is the effect of splitting of a spectral line into several components in the presence of a static magnetic field. It is analogous to the Stark effect, the splitting of a spectral line into several components in the presence of an electric field. Also similar to the Stark effect, transitions between different components have, in general, different intensities, with some being entirely forbidden, as governed by the selection rules.
  Since the distance between the Zeeman sub-levels is a function of magnetic field strength, this effect can be used to measure magnetic field strength, e.g. that of the Sun and other stars or in laboratory plasmas.
  The Zeeman effect is very important in applications such as nuclear magnetic resonance spectroscopy, electron spin resonance spectroscopy, magnetic resonance imaging and Mössbauer spectroscopy. It may also be utilized to improve accuracy in atomic absorption spectroscopy.
  A theory about the magnetic sense of birds assumes that a protein in the retina is changed due to the Zeeman effect.
  When the spectral lines are absorption lines, the effect is called inverse Zeeman effect.
context_section_description: George Ellery Hale was the first to notice the Zeeman effect in the solar spectra, indicating the existence of strong magnetic fields in sunspots. Such fields can be quite high, on the order of 0.1 tesla or higher.  Today, the Zeeman effect is used to produce magnetograms showing the variation of magnetic field on the sun.
caption: Zeeman effect on a sunspot spectral line
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