Our mission
Most moon-phase sites are slow, ad-heavy, and track you across the web. We built Open Moon Calendar to be the opposite: a lightweight, accurate moon calendar that respects your privacy and works everywhere — on any device, in 10 languages, even offline. The only tracking we use is Google Analytics (GA4) to understand aggregate usage — no ad trackers, no data selling.
What we offer
- Moon phases & full moon calendar for 2025, 2026 and beyond, with exact primary-phase times.
- Moonrise & moonset, sunrise & sunset computed for your exact location.
- Sun & Moon Today dashboard — live altitude curves, twilight phases, and horizon bearings.
- Night Sky & Eclipses trackers — upcoming solar and lunar eclipses with local visibility.
- 10 languages, day/night theme, offline mode — no login, no account, no paywall.
How it works
All astronomical calculations run 100% locally in your browser using well-established lunar algorithms (synodic cycle, SunCalc-style solar/lunar position math). Your location never leaves your device — there are no servers processing your coordinates and no advertising trackers bundled with the core experience. Separately, Google Analytics (GA4) measures aggregate page usage so we can improve the site; details and opt-out options are in ourPrivacy Policy.
Who maintains this?
Open Moon Calendar is an independent open web project, maintained by a small team of astronomy and web-performance enthusiasts. The site is static-first (built with Astro), which keeps it fast, cheap to run, and resilient under high traffic.
Get in touch
Found an inaccuracy, want a feature, or need to report an issue? We'd love to hear from you on our Contact & Feedback page. For data-use rules, see our Terms & Conditions and Privacy Policy.