Editing Adaptive optics (section)

=== Atmospheric seeing ===
{{Further|Astronomical seeing}}
[[File:Ao movie.gif|thumb|Negative images of a star through a telescope. The left-hand panel shows the slow-motion movie of a star when the adaptive optics system is switched off. The right-hand panel shows the slow motion movie of the same star when the AO system is switched on. <!--The image of the star is much more compact, and breaks up less with adaptive optics switched on. However, the image of the star also changes shape much more quickly when the adaptive optics system is switched on.-->]]
When light from a star or another astronomical object enters the Earth's atmosphere, atmospheric [[turbulence]] (introduced, for example, by different temperature layers and different wind speeds interacting) can distort and move the image in various ways.<ref>
{{cite conference
|last=Max
|first=Claire
|title=Introduction to Adaptive Optics and its History
|conference=American Astronomical Society 197th Meeting
|url=http://www.cfao.ucolick.org/EO/Resources/History_AO_Max.pdf
}}</ref> Visual images produced by any telescope larger than approximately {{convert|20|cm|m in}} are blurred by these distortions.