Free dark sky window for any location: sun and moon rise/set plus the longest moonless astronomical darkness for tonight's session.
Frequently asked questions
When does astronomical darkness start in Guyana?
It begins after astronomical twilight ends, when the sun is far enough below the horizon that sky glow no longer dominates. Moon phase and moon altitude can shorten or eliminate the moonless window.
Why plan moonless windows for astrophotography?
Moonlight raises sky background brightness and hides faint nebulae and the Milky Way core. Knowing the longest moon-free interval helps you schedule deep-sky or panorama sessions.
Does this include weather?
No. This tool is ephemeris-only (sun, moon, twilight). Pair it with Stargazing Weather for clouds and dew risk on the same night.