Astronomy Calculators
Last updated: October 2026
Distance Modulus Calculator
Compute distance to a celestial object in parsecs from its apparent and absolute magnitudes using the distance modulus formula d = 10^((m − M + 5)/5).
Orbital Velocity Calculator
Compute the orbital velocity around a central body using v = √(GM/r) × √(1+e), an approximation that scales the circular-orbit speed by the eccentricity.
Stellar Distance Calculator
Convert a star's measured parallax angle into its distance in parsecs and light-years using the standard parallax formula.
Redshift Velocity Calculator
Compute the recession velocity of a nearby galaxy from its redshift z using v = c·z, where c is the speed of light.
Stellar Parallax Calculator
Convert a star's measured parallax angle into its distance from Earth in parsecs.
Tidal Force Calculator
Calculate the gravitational force between two celestial bodies separated by a given distance.
Apparent Magnitude Calculator
Convert a star's absolute magnitude and distance in parsecs into its apparent magnitude — how bright it looks from Earth.
Stellar Luminosity Calculator
Compute a star's luminosity in solar units (L☉) from its radius and surface temperature via the Stefan-Boltzmann law.
Planetary Mass Calculator
Determine the mass of a star or planet in solar masses from a satellite's orbital period and semi-major axis.
Habitable Zone Calculator
Estimate the inner edge of a star's habitable zone in AU based on its luminosity relative to the Sun.
Exoplanet Habitability Calculator
Estimate an exoplanet's effective surface temperature and habitability based on its host star and orbital parameters.
Angular Size Calculator
Calculate how large a celestial object appears in the sky given its physical diameter and distance.
Planetary Temperature Calculator
Estimate a planet's equilibrium temperature based on its host star's temperature, radius, and the planet's orbital distance.
Magnitude Difference Calculator
Convert the difference between two stellar magnitudes into a brightness ratio.
Stellar Lifetime Calculator
Estimate how long a star spends on the main sequence based on its mass relative to the Sun.
Telescope Magnification Calculator
Compute the effective magnification of your telescope with any eyepiece and Barlow lens combination.
Astrophotography Exposure Calculator
Calculate the recommended sub-frame exposure time for deep-sky astrophotography based on your telescope, camera, and sky conditions.
Lunar Phase Calculator
Calculate the Moon's current phase and illumination percentage for any calendar date.
Planet Visibility Calculator
Find the best times to observe Jupiter, Saturn, Mars, or Venus from your location.