Night Sky Planner

Enter your ZIP code to find out if tonight is good for stargazing. Get astronomical twilight times, golden hour windows, moon phase, visible satellite passes, current cloud cover, and an overall stargazing quality rating.

Enter a 5-digit US ZIP code to see tonight's sky conditions.

Back to Space Toolkit

What Affects Stargazing Quality

Moon illumination: The single biggest factor for visual astronomy. A full moon washes out all but the brightest stars; a new moon leaves skies dark enough for faint galaxies and nebulae. This tool weights moon brightness at 35% of the overall quality score when weather data is available (40% otherwise).

Cloud cover: Even a clear new moon night is wasted under overcast skies. When available, live cloud cover from the OpenWeatherMap API is factored in at 20% of the quality score and shown as a 12-hour hourly forecast. Clear skies (≤ 20% cloud cover) score highest; overcast (> 75%) scores zero.

Twilight and dark windows: True astronomical darkness begins when the Sun drops 18° below the horizon. The interval between evening and morning astronomical twilight is your dark window — the wider it is, the more time you have under genuinely dark skies. At high latitudes in summer, this window can shrink to zero.

Related space tools: Browse a full month of moon phases, illumination percentages, and rise/set times with the Lunar Phase Calendar. Track the ISS in real time with the ISS Tracker, or predict visible passes for dozens of other satellites with the Satellite Pass Predictor.

This tool was created by Ben Crittenden, a Project Management Professional (PMP) with experience in web development and systems administration.