Explain it like I'm 12
The Moon rises later each day because it moves around Earth while Earth rotates. This foundation calculator estimates Moon age first, then applies the usual daily drift.
Moonrise and Moonset Calculator
Estimate moon age, moonrise and moonset from date and longitude with a clear foundation-level warning about almanac precision.
Why people use this calculator
- Get a rough moonrise planning time before checking an almanac.
- Teach why moonrise shifts later through the lunar month.
- Compare phase age with rough rise and set timing.
Common mistakes
- Treating a rough moonrise estimate as an official local time.
- Forgetting that latitude and horizon height matter.
- Assuming moonrise moves exactly 50 minutes every day.
Citation sentence
CalculationTime estimates moonrise by calculating lunar age from a known new-moon epoch, then applying a rough daily moonrise drift and longitude correction.
Source references
- USNO - Phases of the Moon and rise/set context — official astronomical data reference
- NASA Moon facts — lunar cycle background
Formula
Moon age = days since known new moon modulo 29.530588853. Foundation moonrise estimate = 06:00 + moon age × 50 minutes − longitude × 4 minutes. Moonset estimate is about 12 h 25 min later.
Worked example
For 16 July 2026 near 151.2°E, the calculator estimates lunar age first, then shifts the rough moonrise clock by longitude to produce a local-solar-time planning estimate.
Professional note
Master’s Tip: moonrise is much more location-sensitive than phase. Treat this as a teaching estimate until a full topocentric moonrise engine is added.
Regional and unit assumptions
Standard or basis: civil-time conversion by explicit UTC offset arithmetic. This is a scheduling and worksheet calculator, not an IANA timezone database, airline schedule, legal deadline or payroll compliance record.
Assumptions and limitations
- Foundation planning estimate only, not an official moonrise table.
- Latitude, declination, horizon height, refraction and topocentric parallax are not fully modelled.
- Use an official astronomical almanac for navigation, safety, photography commitments or public claims.
Methodology & Accuracy
How this calculator is checked
CalculationTime pages are built around visible arithmetic: the formula, assumptions, worked example and practical limitations are shown so the result can be checked rather than simply trusted.
Formula used
Moon age = days since known new moon modulo 29.530588853. Foundation moonrise estimate = 06:00 + moon age × 50 minutes − longitude × 4 minutes. Moonset estimate is about 12 h 25 min later.
Standard or basis
Standard or basis: civil-time conversion by explicit UTC offset arithmetic. This is a scheduling and worksheet calculator, not an IANA timezone database, airline schedule, legal deadline or payroll compliance record.
Where a calculator follows a named legal, trade or industry standard, that standard is cited visibly. Otherwise the page uses transparent general arithmetic and states its limits.Master's Tip
Master’s Tip: moonrise is much more location-sensitive than phase. Treat this as a teaching estimate until a full topocentric moonrise engine is added.
Related calculators
Questions
Is this an official moonrise table?
No. It is a foundation estimate for planning and education. Use an official almanac for exact local moonrise and moonset.
Why does moonrise move later each day?
The Moon advances in its orbit each day, so Earth has to rotate a little farther before the Moon rises again.
Why can official moonrise differ?
Latitude, lunar declination, horizon height, refraction and parallax all affect the real local rise time.
Calculation note
Moonrise is a harder problem than moon phase because it depends on local observing geometry. This foundation page makes the rough phase-to-rise relationship visible while warning users to verify exact times.