Photometry & Imaging
Measuring how bright things are and resolving their fine detail — the magnitude system, precision photometry, and the interferometry and adaptive optics that sharpen the view.
In brief
Measuring brightness and resolving detail.
Techniques in this category
- Adaptive OpticsTechniqueMeasures: Sharp images through the atmosphere
Deformable mirrors that flex hundreds of times a second to cancel the blurring of Earth's turbulent atmosphere, giving ground telescopes near space-quality sharpness.
- InterferometryTechniqueMeasures: Fine angular detail
Combining the light of separate telescopes so they act as one much larger instrument, achieving resolution impossible for a single dish. Radio interferometry links antennas across continents; it produced the first images of black-hole shadows.
- PhotometryTechniqueMeasures: The brightness of an object
The precise measurement of the brightness of a star or galaxy, in one or more filters. Photometry over time reveals variable stars, transiting planets, and supernovae; photometry in different colours reveals temperature.
- The Magnitude SystemTechniqueMeasures: Brightness on the magnitude scale
Astronomy's logarithmic, backwards brightness scale, in which smaller numbers are brighter. Apparent magnitude is how bright an object looks; absolute magnitude is how bright it truly is — and the difference gives its distance.
Knowledge connections
- Group includesPhotometry
- Group includesThe Magnitude System
- Group includesInterferometry
- Group includesAdaptive Optics
Sources
The primary and reference sources this topic draws on.
- NASANational Aeronautics and Space Administration
Mission data, planetary science, space telescopes, and public-domain imagery.
Most NASA-produced imagery is in the public domain; individual items are checked for usage terms before publication.