Orbune astronomy tools
Know your night sky
Free astronomy utilities that run in your browser. Search for what you need, or browse the directory below.
All tools
15 tools available
Moon
Reference
- Bortle Scale Simulator, Classifier, and Assessor Explore all nine Bortle classes with an interactive sky simulator, convert limiting-magnitude or SQM readings to a class, and assess your own site.
- Kp Index Reference and Aurora Visibility Estimator Learn what every Kp value from 0 to 9 means, with NOAA G-scale storm levels, and estimate whether aurora could reach your latitude at a given Kp.
- Messier Object List with Data for All 110 Objects Filterable, sortable table of all 110 Messier objects with type, constellation, coordinates, magnitude, size, distance, and best viewing season.
- Telescope Magnification and Eyepiece Calculator Work out magnification, focal ratio, exit pupil, and true field of view for any telescope, eyepiece, and Barlow combination, with honest useful limits.
Sky
- Constellation Finder and Tonight's Visible Constellations Look up any of the 88 IAU constellations to see where it sits in your sky, or list every constellation above your horizon for any place and time.
- Night Sky Tonight: Darkness, Moon, and Planets at a Glance See tonight's darkness timeline, moon phase and rise and set times, naked-eye planet visibility, and the best moonless dark-sky window anywhere.
- Planet Visibility Tonight: Rise, Set Times and Sky Positions See which naked-eye planets are visible tonight from your location, with rise and set times, sky positions, brightness, and plain verdicts.
- Star Chart for Tonight's Sky by Date, Time, and Location Draw an all-sky chart of 463 bright stars, the Moon, and the five naked-eye planets for any date, time, and place, computed in your browser.
Sun
- Equinox and Solstice Calculator (Years 1000 to 3000) Compute the UTC and local-time instants of the equinoxes and solstices for any year from 1000 to 3000, with season lengths and a multi-year table.
- Golden Hour and Blue Hour Calculator Exact morning and evening golden hour and blue hour times for any date and location, with sunrise and sunset anchors.
- Sun Path Diagram for Any Date and Location Chart the sun's altitude and azimuth across the sky for any date and place, with solstice and equinox reference arcs and rise and set bearings.
- Sunrise and Sunset Times Calculator Calculate sunrise, sunset, solar noon, day length, and civil, nautical, and astronomical twilight times for any date and location on Earth.
Time
- Julian Date Converter: Calendar Date to JD and Back Convert calendar dates and UTC times to Julian Dates and back with MJD, day of week, and day of year, using the standard Meeus algorithms.
- Sidereal Time Calculator (GMST and Local Sidereal Time) Convert any date and time from 1800 to 2200 into Greenwich and local mean sidereal time, with a live ticking sidereal clock for your longitude.
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