Astronomy Tools and Calculators
Plan an observing session, explore deep-sky targets, compare telescope and eyepiece setups, work with celestial coordinates and understand Solar System scale with connected astronomy tools.
Start with the conditions and targets that determine tonight’s session
Use a date and location to understand darkness, the Moon, planets and promising deep-sky targets, then move into target or equipment tools when you need more detail.
Night Observation Planner
Estimate twilight, Moon position, planet visibility and well-placed deep-sky targets for a chosen location and date.
Open tool →ToolMoon Observing Planner
Interpret lunar phase and illumination for lunar detail and deep-sky contrast.
Open tool →ExplorerDeep-Sky Object Explorer
Search Messier targets by type, season, constellation, brightness, angular size and local sky position.
Open explorer →Compare complete optical setups instead of looking at magnification alone
Aperture, exit pupil and field of view often matter as much as power. These tools keep those relationships together.
Telescope Setup Calculator
Calculate magnification, focal ratio, exit pupil, true field and theoretical resolution from one setup.
Open tool →ToolEyepiece Comparison
Compare up to four eyepieces on the same telescope and see how the useful optical values change together.
Open tool →ToolEyepiece Field of View Simulator
Compare a target’s angular extent with the estimated eyepiece field.
Open tool →Check sampling and framing before an imaging session
Camera pixels and focal length determine image scale, while sensor size determines the sky area captured in each exposure.
Pixel Scale and Sampling
Calculate arcseconds per pixel, sensor field and sampling relative to entered seeing.
Open tool →ToolCamera Field of View Simulator
Compare sensor framing with the Moon and deep-sky targets using telescope focal length and sensor dimensions.
Open tool →GuideSeeing vs Transparency
Understand why atmospheric steadiness and sky clarity affect imaging and visual observing differently.
Open guide →Turn catalogue positions into a local position in the sky
Right ascension, declination and sidereal time connect star catalogues with an observer’s altitude and azimuth.
RA/Dec to Alt/Az
Convert catalogue coordinates into a local sky position for a location and UTC time.
Open tool →ToolJulian Date and Sidereal Time
Calculate JD, MJD, Greenwich sidereal time and local sidereal time.
Open tool →GuideCelestial Coordinates Explained
Understand how right ascension and declination relate to altitude, azimuth and transit.
Open guide →Compare worlds and make large astronomical numbers easier to interpret
The same planetary dataset powers exploration and comparison so physical values remain consistent across experiences.
Solar System Explorer
Inspect physical and orbital data for all eight planets.
Open tool →ToolPlanet Comparison
Compare two planets across size, mass, density, gravity, day, year and escape velocity.
Open tool →ToolPlanet Size Comparison
Compare planetary diameters with proportional visual discs.
Open tool →ToolLight Travel Time
Translate a distance into the time light needs to cross it.
Open tool →ToolAstronomy Distance Converter
Convert AU, light-years, parsecs and everyday distance units.
Open tool →ReferenceAstronomy Constants Reference
Look up the standard units and constants used by astronomy calculations.
Open reference →Use simple educational tools when the goal is understanding rather than session planning
These experiences remain useful entry points, but they sit separately from the observing and equipment workflow.
Moon Phase Today
Calculate lunar phase, illumination and age for a date.
Open tool →ToolAge on Other Planets
Compare elapsed age using each planet’s orbital year.
Open tool →ToolWeight on Other Planets
Compare gravitational force using each planet’s reference gravity.
Open tool →ToolKepler’s Third Law Explorer
Change orbital distance and see how the orbital period responds.
Open tool →