Starfinder
A pocket sextant for the web
Starfinder is a free, browser-based augmented-reality star map. Hold your phone up to the sky and the screen overlays the real-time positions of stars, planets, the Sun, and the Moon onto whatever direction it's pointing.
How to use Starfinder
- Open starfinder.pages.dev in Safari on iPhone or Chrome on Android.
- Tap Begin Observation and grant location plus motion-sensor permissions.
- Hold your phone like a window to the sky. Aim the crosshair at any star to read its name, distance, and spectral character.
What you'll see
- 8,920 Hipparcos stars to naked-eye magnitude 6.5, color-tinted by B-V index.
- Sun, Moon (with current phase), and the planets Mercury, Venus, Mars, Jupiter, Saturn, Uranus, and Neptune.
- Curated constellation lines for Orion, the Big Dipper, Cassiopeia, Cygnus, Lyra, Scorpius, Leo, Taurus, Gemini, Pegasus, Crux, and more.
- A horizon line with cardinal markers and a compass tape across the top.
Why it's accurate
Apparent positions are computed by Don Cross's astronomy-engine — full precession, nutation, aberration, and atmospheric refraction. The compass is corrected to true north using the NOAA WMM2025 geomagnetic model. You can calibrate even further by aiming the crosshair at any known star and tapping Lock.
Pricing
Free for the live sky and everything above. $3 one-time unlocks a time-travel scrubber to view the sky on any past or future date — useful for birth-night charts, planning observations, or seeing what Galileo saw.
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