Methodology and Limitations
The tool is designed for an initial decision about the night and time, not to replicate professional astronomy software or forecast the weather.
Astronomical calculations
We use simplified astronomical formulas to calculate the position and altitude of the Sun and Moon from the city’s coordinates, along with estimates of the Moon’s phase and the galactic core’s altitude. The accuracy is suitable for planning a general window, not for precise scientific work.
Suitability score
The score depends on your goal. The Milky Way needs darkness, a suitable galactic core altitude and little moonlight. General observing and meteors focus more on darkness and the Moon. Moon photography treats the Moon being above the horizon as a positive factor.
Driving time doesn’t raise the score
The driving time you choose is not part of the astronomical calculation, and we don’t use it to claim you will automatically reach darker skies. The first version has no licensed, accurate light-pollution layer linked to roads.
What the result does not include
There is no live weather, dust, humidity, live Bortle measurement, road condition or access permit information. These must be checked separately before your trip.
Testing against external sources
We periodically check our calculations against sunrise/sunset and moonrise/moonset tables published by independent astronomical sources. Because the formulas are simplified, we present the result as an approximate window and don’t claim observatory-level precision to the minute or degree.