How to Use MoonCalc to Check Moon Position, Phase, and Rise/Set Times for a Location

Updated

MoonCalc (mooncalc.org) is a free browser-based tool that shows the Moon's motion and phase for a specific day and location. To use it, set latitude, longitude, height, and time zone, pick a date, then read the map and time slider for moonrise, culmination, moonset, altitude, azimuth, distance, and shadow length. It suits planning observations, checking historical or future dates, and understanding where the Moon will be at a given moment. No account is required to use the page; the site accepts optional donations via PayPal.

What MoonCalc Shows

The page combines a map, a time slider, and a data panel. According to the site's own help text, MoonCalc displays the motion of the Moon and its phase for a particular day at a particular location. You can see moon positions at moonrise, at a selected time, and at moonset.

Element What it tells you
Yellow curve on the map The Moon's trajectory across the sky for that day
Moon position near the center The closer the Moon is to the middle, the higher it is above the horizon
Time slider colors Moonlight during the day
Data panel Moonrise, culmination, moonset, distance, altitude, azimuth, shadow length
Extended data JDE, DeltaT, GMST, GHA, declination, right ascension, next perigee, next apogee

Step-by-Step: Get Lunar Data for Your Location

  1. Enter coordinates. In the header, fill in Latitude (Lat) and Longitude (Lon). You can also use the "Set Lat/Lon" option in the geo data section, which additionally shows UTM coordinates for the selected point.
  2. Set height. Enter the elevation of your location in meters. This feeds into altitude and shadow-length calculations.
  3. Choose the time zone and DST. Select the correct TimeZone and the daylight saving (DST) setting. This is the most common source of wrong results — see the troubleshooting section below.
  4. Pick a date. Use the month and day controls, and the time field, to select the moment you care about. The date range selector covers historical periods going back to -1999 and forward through 0101 and beyond.
  5. Read the results. The "Lunar data for the selected location" panel shows Moon Rise, Moon Culmination, Moon Set, Moon Distance, Moon Altitude, Moon Azimuth, and Shadow Length. Shadow length is given for an object level you specify in meters.
  6. Move through the day. Drag the Moon on the time slider with the mouse, or use the keyboard arrow keys, to watch altitude and azimuth change hour by hour.

Expected result: for your coordinates and date, you get the three key events (rise, culmination, set) plus the Moon's position and shadow length at the selected time, with the trajectory drawn on the map.

Reading the Map and Time Slider

The map is not a sky chart in the photographic sense — it is a top-down view where the yellow curve traces the Moon's path for the day. The position of the Moon relative to the center encodes altitude: near the middle means high in the sky, toward the edge means low or below the horizon. The time slider's colors indicate whether the selected moment is in daylight or moonlight, which helps you judge visibility without a separate sunrise/sunset lookup.

If you want to compare the Sun's behavior at the same location, the site points to suncalc.org; for planets it points to planetscalc.org, and for satellites to orbtrack.org.

Live Mode and Reverse Calculation

  • Live mode updates the display continuously for the current moment. To stop it, click the "STOP-LIVE" button — the page states this explicitly, so if the data seems frozen on "now," that button is the way out.
  • Reverse Calculation works backward from a Moon position to the time it occurs, which is useful when you know where you expect the Moon to be (for example, above a landmark) and want the corresponding clock time.
  • Moon Calendar gives a calendar view of lunar phases for planning across days or months.
  • Print options let you output the current data or the current map, handy for field notes.

Common Problems and Fixes

Symptom Likely cause Fix
Rise/set times off by an hour or more Wrong time zone or DST setting Recheck TimeZone and the DST field against your location's actual offset on that date
Moon shown below horizon when you can see it Coordinates entered in the wrong order or wrong hemisphere sign Verify Lat/Lon signs (south and west are negative in decimal convention)
Display not updating Live mode still running or stopped Use STOP-LIVE to end live mode, then set the time manually
Shadow length looks wrong Object level not set Enter the object height in meters in the shadow-length field
Historical date gives unexpected results Time zone rules differ for old dates Treat very old dates as approximate and cross-check the DeltaT value shown in the extended data

When MoonCalc Is the Right Tool

Use MoonCalc when you need location-specific lunar geometry — position, altitude, azimuth, rise/set, and shadow length — for a chosen date, including historical dates. It is a good fit for photographers planning a Moon alignment, for educators demonstrating the Moon's daily path, and for anyone checking whether the Moon will be up at a given hour. If you mainly need phase calendars rather than positional data, the Moon Calendar view covers that; if you need the Sun's or planets' positions, the sister sites are the better destination.