Nyx: Dark Sky Planner

Make time for a darker sky. Nyx compares nights across the 63 US national parks. Moonlight, cloud cover, estimated sky glow and the length of true darkness become one Darkness Score from 0 to 100, with a breakdown that explains it. PLAN Find nearby parks within a straight-line radius, or sort every park by tonight's darkness. Browse the calendar's five-night new moon window. Follow thirty nights on a timeline that draws in the range the forecast models allow. Give the trip planner your free dates and it suggests a park for each night. Times are park-local. SEE WHAT IS UP Each park's night lists the Milky Way core with its rise, highest point, direction and Moon-free hours; planets with rise and set times; meteor showers with the Moon's interference and a rate estimate from the International Meteor Organization; and lunar eclipses the park can see. These are reasons to go. They never change the score. A FORECAST THAT SAYS WHAT IT DOES NOT KNOW Nyx compares three weather models and tells you when they agree and when they do not. It separates thin high cloud from thick low cloud, notes dew, cold and wind for the dark hours, and shows wildfire smoke and haze beside the score. Beyond the forecast horizon Nyx scores the Moon and darkness alone, and labels those nights that way. FIELD MODE At the park, "I'm here tonight" opens a red, dimmed screen made for night-adapted eyes: the countdown to true darkness, each milestone of the night, and a dark-adaptation clock. "Where to look" turns the real sky to your iPhone's direction, with no camera. A Live Activity keeps the countdown on the Lock Screen, and alarms can wake you for true darkness or the core's rise (iOS 26.1 and later). On Apple Watch, the countdown and the Moon are on your wrist, in red. On Apple Vision Pro, you can stand under the real sky for a park and a night. SKY GLOW Each named viewing spot shows how its sky glow compares with the other national parks, from NASA Black Marble night-lights data, and each park names the direction of the city glow on its horizon. It compares places; it is not a measurement taken at the spot. KEEP A LITTLE OF THE NIGHT Save parks and receive optional local reminders for promising nights. Keep a private journal with notes and selected photos; each night becomes a star in your own constellation. Widgets show the best sky among your saved parks. BUILT FOR MORE PEOPLE Nyx works with VoiceOver, larger text, Reduce Motion, Reduce Transparency, Increase Contrast and Bold Text. Audio graphs let you hear the timeline, the calendar and the sky arc. Haptics follow the Moon's phase. Step-free viewing spots are marked and can be filtered. Night-vision mode renders everything in red. Spanish is included. PRIVATE BY DESIGN No account, no advertising, no tracking. Your location and your journal stay on your device. Three optional services supply data, each with its own switch under Your privacy: park alerts from the National Park Service, forecasts from Open-Meteo, and smoke and haze from Open-Meteo's air-quality service. They receive the public coordinates of national parks, not yours. WORKS OFFLINE Moon, sun and twilight calculations, the core, planets, the park library, the calendar, the journal and saved parks work without a connection. Forecasts reach about sixteen days. Moonrise and moonset are approximate, to about 15 minutes. PLEASE NOTE Scores do not confirm clear skies or safe access. Check current road and park conditions before traveling. Park alerts and ranger programs come from the National Park Service and may be unavailable. Weather data: Open-Meteo, CC BY 4.0. Air quality: Copernicus Atmosphere Monitoring Service via Open-Meteo, CC BY 4.0. Night lights and Moon imagery: NASA. Meteor showers: International Meteor Organization. Lunar eclipses: Fred Espenak, NASA/GSFC. Park data: National Park Service. Nyx is not affiliated with or endorsed by the National Park Service or NASA.