Sky science
Rayleigh Criterion
Direct answer
Rayleigh Criterion: The Rayleigh Criterion conventionally resolves two point sources when one diffraction maximum falls on the other’s first minimum.
It is one standard threshold for separating diffraction patterns.
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At a glance
- Found in
- Astronomy & Skywatching
- Related
- Resolving Power, Diffraction Limit, Telescope Aperture, Telescope Focal Length
It is one standard threshold for separating diffraction patterns.
A scientific orientation to scale, light, or motion; the article supplies the precise definition.
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The story behind Rayleigh Criterion
Lord Rayleigh formalized resolution criteria within nineteenth-century wave optics.
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Why Rayleigh Criterion matters
Rayleigh Criterion turns a gradual visibility problem into a useful numerical comparison.
Rayleigh Criterion in practice: an example
For a circular aperture the angle scales approximately as 1.22 wavelength divided by diameter.
Where readings of Rayleigh Criterion go wrong
Real detectors and image processing can use other definitions.
Sources and editorial method
Research references used for this entry include:
- European Southern Observatory: Technology for Telescopes - Observatory reference for aperture, angular resolution, atmospheric seeing, mirrors, and telescope technology.
- NASA Science: Universe Glossary - NASA definitions for common stellar, galactic, orbital, and high-energy astronomy terms.
- Source
- The Great Almanac Dictionary
- Category
- Astronomy & Skywatching
- Last updated
- 2026-09-26
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Common questions
What is the Rayleigh Criterion?
The Rayleigh Criterion conventionally resolves two point sources when one diffraction maximum falls on the other’s first minimum.
What do people get wrong about the Rayleigh Criterion?
Real detectors and image processing can use other definitions.
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