Moon Theory

Moon Theory is a quiet, private observatory for your pocket. Everything is computed right on your device — no account, no sign-in, no analytics, and no data collected, ever.

TODAY

A large, live moon glyph drawn from the real illuminated fraction, with phase name, illumination, moonrise and moonset, and countdowns to the next new and full moon. A "through the telescope" card shows tonight's terminator and libration — where along the lunar limb to point your optics.

TONIGHT

Your observing plan, assembled automatically. The dark-sky window between dusk and moon interference, tonight's best deep-sky targets for your sky, visible planets, a seeing forecast built from jet-stream winds, active meteor showers, ISS passes, and an evening timeline.

SKY

A live star map of your sky right now. Pinch to zoom from wide field down to 20°, pan around the horizon, and tap any star, planet, or deep-sky object for its field card. Constellation and ecliptic overlays help you find your way. Red night mode preserves your dark adaptation at the eyepiece.

CALENDAR

A month grid with a phase glyph on every day; new, quarter, and full days marked. Tap any day for its phase and rise/set times.

ALERTS

Local notifications, on your terms: phase events with custom lead times, moonrise and moonset alarms, ISS passes over your location, meteor-shower peaks, and aurora watches when geomagnetic activity spikes.

IT TEACHES AS YOU GO

Every number explains itself in plain language, and unfamiliar terms unfold into two-sentence field notes when tapped. Each night the app surfaces one earned insight about your sky.

Swipe between tabs or tap the bar — the whole app is built for one-handed use in the dark.

PRIVATE BY DESIGN

No account, no analytics, no tracking, no ads — and nothing about you is ever collected or stored remotely. The core app is fully offline: moon, planets, stars, and calendar all compute on-device. Online extras — cloud and seeing forecasts, space weather, satellite orbits — are fetched anonymously with no identifiers: the forecast request carries your coordinates and nothing else, the response is used once, and nothing about you is retained. Off the grid, the app quietly falls back to everything it can compute offline.

Whether you're planning tonight's session at the eyepiece or just love knowing what the sky is doing, Moon Theory keeps the night at your fingertips — quietly, accurately, privately.