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Astronomy & optics

Explore distances, orbital periods, telescopes and apparent brightness. These models illustrate relationships without retrieving current ephemerides.

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15 calculators

15 calculators available.

Astronomy & opticsLight travel time in a vacuumCalculate the time light takes to travel a distance and compare one-way with round-trip travel.
Astronomy & opticsTelescope magnification calculatorCalculate magnification from telescope and eyepiece focal lengths, with an optional Barlow or reducer factor.
Astronomy & opticsTelescope exit pupil calculatorFind the diameter of the emerging light beam from aperture and magnification.
Astronomy & opticsTelescope true field of viewEstimate the visible patch of sky from the eyepiece’s apparent field of view and magnification.
Astronomy & opticsAngular size from size and distanceCalculate the angle subtended by a length perpendicular to the line of sight.
Astronomy & opticsAstrophotography image scale and field of viewCalculate arcseconds per pixel and the horizontal field of view from pixel size, sensor resolution and focal length.
Astronomy & opticsRedshift from wavelengthsCompare observed and emitted wavelengths to calculate the dimensionless redshift z.
Astronomy & opticsDistance modulus and apparent magnitudeCalculate apparent magnitude from absolute magnitude, distance and specified extinction.
Astronomy & opticsSimplified exoplanet transit depthEstimate the relative dimming during the full transit of a dark planet across a uniformly bright stellar disc.
Astronomy & opticsLuminosity and radiative fluxCalculate the power per unit area at a distance from a source emitting equally in all directions.
Astronomy & opticsPhoton energy, frequency and photon rateCalculate a photon’s energy and frequency from its vacuum wavelength, and the photon rate of monochromatic radiation.
Astronomy & opticsRefraction and total internal reflectionCalculate the refracted angle from refractive indices and the angle of incidence, and check for total internal reflection.
Astronomy & opticsThin lens: image distance and magnificationCalculate image position and magnification for an ideal thin lens and a real object.
Astronomy & opticsDiffraction angle of an optical gratingFind the angle of a diffraction order from wavelength and the line density of an ideal grating.
Astronomy & opticsDouble-slit interference fringe spacingEstimate the spacing of adjacent bright fringes near the centre of a double-slit pattern.