Prohowich Martian Calendar
The complete Mars calendar — MY −0199 to MY 1500 — built for accuracy, not fiction.
Prohowich Martian Calendar converts any Earth date to its precise Mars equivalent using the Mars Solar Date (MSD) system — no guessing, no approximation.
What It Does
- Shows the current Mars date, time (AMT — Airy Mean Time), and sol count in real time
- Browse any Mars Year from MY −0199 to MY 1500
- 24-month Martian calendar with fixed month lengths per century, recalculated each century to account for Mars orbital precession
- Season tracking: Northern and Southern hemisphere views
- Lₛ×15° milestone table — every orbital checkpoint with AMT time
- Full year view with orbital events: equinoxes, solstices, Aphelion, Perihelion
- Earth↔Mars time converter
- Complete Mars Year table with MNYD, MSD, sol counts, and all seasonal markers
- Three day-of-week naming systems: Earth, Numerical (Greek ordinals), Mars Planetary
The Calendar System
Month lengths are fixed within each Martian Century (~100 Mars years, ~188 Earth years), then recalculated for the next century using actual Lₛ crossing times. Every Lₛ×15° milestone is guaranteed to fall within its correct month. Regular years = 668 sols; augmented (leap) years = 669 sols, with the extra sol added to Month 24.
The Icon
38χ marks when the app became viable — Mars Year 0038, Month 22 (Χ: Charmē). The background is Mars. The ring shows all 24 months by season color, sized by sols per month.
At a Glance
- Real-time Mars clock — Current AMT updated live
- MY −0199 → MY 1500 — 1,700 Mars years of coverage
- 24 named months — Greek letters + etymology
- Season-aware — Switch N/S hemisphere instantly
- Orbital events — Equinoxes, solstices, Aphelion, Perihelion
- Time converter — Earth UTC ↔ Mars AMT (also as a widget)
Frequently Asked Questions
What is the Prohowich Martian Calendar app?
An Android app that converts any Earth date to its precise Mars equivalent using the Mars Solar Date (MSD) system. It covers Mars Year −0199 through MY 1500 — 1,700 Mars years of calendar data.
Does the app collect any personal data?
No. There are no ads, no accounts, and no data collected. The app only saves two preferences locally on the device — the day-of-week naming system and hemisphere view. See the full Privacy Policy.
How many months are in a Martian year, and how long is a sol?
The Martian calendar has 24 months. A regular Martian year is 668 sols long; an augmented (leap) year is 669 sols, with the extra sol added to Month 24.
What does AMT stand for?
AMT stands for Airy Mean Time — the app’s Mars time-of-day standard, equivalent to Greenwich Mean Time on Earth.
No ads. No accounts. No data collected. Two preferences saved locally. See the full Privacy Policy.
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