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Astronomy Tools

Telescope, orbit and stargazing math. 20 free tools, no sign-up.

Telescope Magnification CalculatorDivide telescope focal length by eyepiece focal length to find power, plus your maximum useful magnification from aperture.Telescope Focal Ratio CalculatorFind the f-number of a telescope from focal length and aperture, or solve for the focal length needed to hit a target f-ratio.Telescope Resolving Power CalculatorFind the Dawes and Rayleigh limits in arcseconds from your aperture to judge the finest double star split your scope can show.Telescope Exit Pupil CalculatorFind the exit pupil in millimeters from aperture and magnification, or from eyepiece focal length and focal ratio, to match your eye.CCD Pixel Scale CalculatorFind arcseconds per pixel from your camera pixel size and telescope focal length to check if you are matched to seeing.Angular Size CalculatorFind how large an object appears in the sky in degrees, arcminutes and arcseconds from its true diameter and distance, or solve for size.Escape Velocity CalculatorFind the speed needed to escape a planet, moon or star from its mass and radius using the square root of two GM over r.Orbital Period CalculatorFind how long a satellite or moon takes to orbit a body from the central mass and orbit radius using Newton form of Kepler third law.Kepler Third Law CalculatorConvert between orbital period in years and semi-major axis in astronomical units where P squared equals a cubed.Schwarzschild Radius CalculatorFind the event horizon size of a black hole from its mass using two GM over c squared, in meters, kilometers and solar masses.Redshift Velocity CalculatorConvert a spectral redshift z into recession velocity using both the simple Doppler and relativistic formulas, in km/s and fraction of light.Absolute Magnitude CalculatorConvert between apparent and absolute magnitude using the distance modulus, and solve for distance in parsecs and light years.Star Brightness Ratio CalculatorConvert a magnitude difference between two stars into how many times brighter one is using the Pogson ratio of 2.512.Light Travel Time CalculatorFind how long light takes to cross a distance and convert light years, light minutes and light seconds into kilometers and miles.Parsec to Light Year ConverterConvert between parsecs, light years, astronomical units and kilometers for astronomical distances, both directions instantly.Telescope Limiting Magnitude CalculatorEstimate the faintest star your telescope can show from its aperture, so you know what deep sky targets are within reach.Planet Orbital Speed CalculatorFind how fast a planet moves around the Sun from its orbital radius using the vis-viva circular speed formula, in km/s and mph.Surface Gravity CalculatorFind the gravitational acceleration at the surface of a planet, moon or star from its mass and radius using g equals GM over r squared.Wien Law Peak Wavelength CalculatorFind the peak emission wavelength of a star or blackbody from its temperature, and see the color band it falls in, using the displacement law.Stellar Luminosity CalculatorFind a star total energy output from its radius and surface temperature with the Stefan-Boltzmann law, in watts and solar luminosities.

Free astronomy tools: telescope magnification, focal ratio, exit pupil, pixel scale, escape velocity, orbital period, redshift and stellar luminosity calculators. All 20 tools are free, run entirely in your browser, and need no sign-up.

Frequently asked questions

Are these astronomy tools free?

Yes. Every astronomy tool on yourhack.ai is completely free, with no sign-up and no usage limits.

Do these astronomy tools work on mobile?

Yes. They run in any modern web browser on phone, tablet or desktop. There is nothing to install.

Is my data private?

Yes. These tools run entirely in your browser, so nothing you enter is uploaded to a server.

How many astronomy tools are there?

There are currently 20 free astronomy tools here, and we add more regularly.

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