Editing Angular resolution (section)

{{short description|Ability of any image-forming device to distinguish small details of an object}}
{{about|optics and imaging systems|angular resolution in graph drawing|angular resolution (graph drawing)}}
{{More citations needed|date=January 2012}}
[[File:Event Horizon Telescope and Apollo 16.png|thumb|A series of images representing the magnification of [[M87*]] with an [[angular size]] of some [[microarcsecond]]s, comparable to viewing a tennis ball on the Moon (magnification from top left corner counter−clockwise to the top right corner).]]
'''Angular resolution''' describes the ability of any [[image-forming device]] such as an [[Optical telescope|optical]] or [[radio telescope]], a [[microscope]], a [[camera]], or an [[Human eye|eye]], to distinguish small details of an object, thereby making it a major determinant of [[image resolution]].  It is used in [[optics]] applied to light waves, in [[antenna (radio)|antenna theory]] applied to radio waves, and in [[acoustics]] applied to sound waves.  The colloquial use of the term "resolution" sometimes causes confusion; when an optical system is said to have a high resolution or high angular resolution, it means that the perceived distance, or actual angular distance, between resolved neighboring objects is small. The value that quantifies this property, ''θ,'' which is given by the Rayleigh criterion, is low for a system with a high resolution. The closely related term [[spatial resolution]] refers to the precision of a measurement with respect to space, which is directly connected to angular resolution in imaging instruments.  The '''Rayleigh criterion''' shows that the minimum angular spread that can be resolved by an image-forming system is limited by [[diffraction]] to the ratio of the [[wavelength]] of the waves to the [[aperture]] width.  For this reason, high-resolution imaging systems such as astronomical [[telescope]]s, long distance [[telephoto lens|telephoto camera lenses]] and [[radio telescope]]s have large apertures.