Retrograde: Tracking Mercury

Two centuries (633 Mercury retrograde cycles) of NASA/JPL Horizons-derived events in app, with geocentric vectors. Full Instrument unlocks granular alerts.

Retrograde carries its astronomical record with it.

633 Mercury retrograde cycles from 1900 through 2100, derived from NASA/JPL Horizons geocentric vectors all bundled inside the app. Status comes from that embedded event table. Current measurements and additional event estimates are calculated on your device. There is no server between the question and the answer.

IS MERCURY IN RETROGRADE?

For some, it's a simple yes or no question. For Retrograde, it's the shades in between that matter.

Retrograde opens the record for today: current phase, apparent longitudinal velocity and acceleration, distance from Earth, solar elongation, illuminated fraction, and the next state change. An orrery shows Mercury's ecliptic position. A fixed-scale velocity plot makes the station crossings visible and marks today on the curve.

TWO CENTURIES OF DATA ON YOUR DEVICE

Select and share any date from 1900 through 2100. Full Instrument opens the complete cycle archive. Read a cycle's complete chronology: shadow boundaries, stations, peak retrograde speed, inferior conjunction, closest approach, and greatest elongations. Compare its duration with all 633 cycles. Add a selected window to Calendar.

NINE NOTIFICATION EVENTS, INDIVIDUALLY CONTROLLED

Full Instrument lets you choose any combination of nine Mercury events for notifications: pre-retrograde shadow begins, greatest eastern elongation, station retrograde, peak retrograde speed, inferior conjunction, closest approach to Earth, station direct, greatest western elongation, and post-retrograde shadow ends.

Each selected occurrence fires once at its event time. Station and shadow alerts use timestamps from the bundled event table. Velocity and geometry alerts use clearly identified on-device estimates. Every alert explains what happened and identifies the next selected event. Events on the same day are combined into one useful update. A custom sound marks delivery. There are no daily reminders or recurring check-ins.

PRIVATE BY DESIGN

The answer, archive, calculations, widgets, alerts, and card generation are local. Retrograde has no account, backend, runtime astronomy feed, ads, analytics, tracking, or subscription. The core instrument works offline.

TODAY STAYS FREE. FULL INSTRUMENT IS ONE PURCHASE.

Today, the animated orrery, current measurements, any-date reports, sharing, and widgets are free. Full Instrument is one permanent purchase that unlocks the complete cycle archive, detailed cycle records, Calendar export, and all nine event alerts. Existing paid owners keep full access automatically. There is no subscription.