Moon calendar
The darkest nights of the coming weeks – ideal for planning deep-sky sessions around new moon. Add a location to also see the actually moon-free dark windows per night.
Tip: enter a location to see the moon-free dark window per night (a bright moon that sets early still leaves a dark night).
What is a “dark window”?
The dark window is the time when it is dark enough for deep-sky at your location. How dark “dark enough” is you set via the threshold above: −18° (astronomical night, truly pitch-black), −15° (a compromise) or −12° (end of astronomical twilight – in midsummer often the best you can get). If the Sun never reaches the chosen depth, it shows “no real darkness” – a looser threshold then reveals usable windows again.
The moon-free dark window is the part of it during which the Moon is also below the horizon – the actually usable time. “Dark window fully moon-free” means: no Moon interferes during the entire darkness, even if that darkness itself is short.
Moon phase and position are computed locally (no API call) and refer to your location.
DateMoon illumination (%)