Linked astronomy tools
Quick start (3 steps)
- Set location, date, and timezone.
- Optionally adjust horizon correction.
- Read moon age/illumination, rise/set, and altitude curve.
Inputs
Results
| Moon age (days) | — |
|---|---|
| Moon illumination fraction | — |
| Phase name | — |
| Moonrise | — |
| Moonset | — |
| Moon transit | — |
| Peak moon altitude (deg) | — |
| Resolved TZ | — |
Moon altitude chart
Definitions & notes
- Moon rise/set in v1: crossing of moon center altitude through 0° (with horizon correction).
- Azimuth: N=0°, E=90°, S=180°, W=270°.
- Altitude: horizon=0°, zenith=+90°.
- Longitude sign: east positive, west negative.
- Moon illumination fraction is 0..1.
How to use moon-visibility effectively
Use this page to compare rise/set times, peak altitude, and illumination for one location and date. It is best for first-pass observing checks and classroom explanations.
Suggested workflow
Check the latitude, longitude, date, and time zone first. Then review the visibility summary, the event table, and finally the altitude chart so each section answers a different question.
Important limits
Illumination alone does not guarantee good observing conditions. Altitude, sky brightness, horizon obstruction, and local weather still matter for practical planning.
See also
FAQ
What does moon illumination fraction mean?
It is the fraction of the lunar disk lit by sunlight, expressed as 0.0 to 1.0. This does not include atmospheric extinction or local seeing.
Why can moonrise or moonset be missing?
At some latitudes and dates, the moon can stay continuously above or below your local horizon correction line, so no crossing happens in the selected day.
Can I use moon illumination to infer visibility quality?
Use this as a first-pass filter, then combine with altitude, air mass, and phase constraints in Observability time plotter for practical planning.