Plan a darker night.

The story

National parks recorded more than 323 million recreation visits in 2025¹, and night is part of why people come: in a survey at Acadia, nearly 90 percent of visitors agreed that viewing the night sky was important to them². Yet a trip to see the Milky Way still fails for reasons no single app joined together: a bright Moon, a cloud deck, the glow of a distant city, or a closed road. Nyx asks one question, where should I go and on which night, and answers it with a Darkness Score for each park and night, explained in four plain parts. It runs its astronomy on the device, says what it does not know, and collects nothing.

Fact sheet

What it does

• One Darkness Score per park per night, from 0 to 100: the Moon (40), clouds (25), sky glow (20) and the hours of true darkness (15), with the weakest one allowed to cap the rest, so an overcast night can never read as good.
• Where and when. Tonight's darkest parks within a straight-line radius; a month calendar with the best stretch of nights; a thirty-night time river whose Moon changes shape as you scrub; and a planner that suggests a park for each of your free nights.
• Closures beside the score. National Park Service alerts sit next to the number, because a dark sky is no use behind a closed road.
• An honest forecast. Three weather models compared, with the range drawn when they disagree; cloud layers, dew, cold and wind for the dark hours; wildfire smoke that can cap the score. Beyond about three days the forecast is eased toward each park's usual clouds for the month, and those nights say so.
• What's up tonight. The Milky Way core timed for each park, planets, meteor showers with a rate range, and lunar eclipses the park can see.
• Field mode. At the park, a red, dimmed screen counts down to true darkness, tracks how long your eyes have adapted, and turns the real sky to wherever you point the phone, with no camera. A Live Activity, alarms and a Control Center control come with it.
• Apple Watch. Tonight's score with the Digital Crown to look ahead, a thirty-minute dark-adaptation clock that taps your wrist, and complications that turn red at dusk.
• Apple Vision Pro. Stand under a park's computed sky on a chosen night, with star names and constellation figures, turn the night by hand, and place the Moon, lit at its true phase, on your table.
• A private journal with notes and selected photos; each night becomes a star in your own constellation. It can be exported as a file you keep.

Accessibility

• VoiceOver: every custom control, including the dial, the Moon, the time river, the sky arc and the calendar nights, speaks a summary of its data. Audio graphs let you hear a month of darkness.
• Sound and touch: "Listen to tonight" plays the shape of the night as tones with a transcript; haptics can follow the Moon's phase.
• Text and display: designed for the largest accessibility text sizes, Reduce Motion, Reduce Transparency, Increase Contrast and Differentiate Without Color.
• Night-adapted eyes: a red mode for the whole app, with measured contrast (red text on black 6.2:1).
• Getting there: step-free notes for viewing spots, each quoting the park's own accessibility page.
• Evidence, stated plainly: Apple's automated accessibility audit passes on every screen in both palettes in the simulator. Testing on physical devices, and with people who use assistive technologies, is the next step and not yet complete.

Boilerplate

50 words

Nyx is a free app that tells you where and when the sky will be darkest across the 63 US national parks. It turns the Moon, the clouds, the sky glow and the hours of true darkness into one score, works offline, and collects no data. One developer made it.

100 words

Nyx is a free dark-sky planner for the 63 US national parks, on iPhone, iPad, Apple Watch and Apple Vision Pro. For every park and night it gives a Darkness Score from 0 to 100, built from the Moon, the clouds, the sky glow and the hours of true darkness, and it explains the score in four plain parts. Park closures sit beside the number. The astronomy runs on the device, so the Moon, twilight and the Milky Way work offline. Nyx says what it cannot know, has no account, advertising or tracking, and collects no data.

200 words

Nyx is a free dark-sky planner for the 63 US national parks. It answers the question that decides a night under the Milky Way: where should I go, and on which night? For every park and night, Nyx gives a Darkness Score from 0 to 100. The Moon, the clouds, the sky glow and the hours of true darkness each add points, and the weakest of them can cap the total, so an overcast night never looks good. The score is explained in four plain parts, and park closures from the National Park Service sit beside it. Nyx is honest about uncertainty. It compares three weather models and draws the range when they disagree. Nights too far ahead for a forecast use each park's usual clouds and say so. Light pollution is called an estimate. At the park, field mode turns the screen red and dim, counts down to true darkness and shows where to look, with no camera. Nyx also runs on Apple Watch and Apple Vision Pro. The astronomy runs on the device. There is no account, advertising or tracking, and the App Store label reads Data Not Collected. One independent developer made it.

Images

Real captures from the app, with captions. Select an image for the full-size file. These come from the pre-release build 1.1 (7); some scores in them were computed before the final scoring rules and will be replaced with captures from the release build. The journal frame uses sample entries.

App icon

Nyx app icon, 1024 × 1024 PNG. Please show it unaltered, on a dark background.

iPhone (1320 × 2868)

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iPad (2064 × 2752, shown smaller)

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Apple Watch (422 × 514)

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Apple Vision Pro (3840 × 2160, shown at 1920)

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The Moon in these images is drawn from NASA data and the stars from the Yale Bright Star Catalogue. Please do not add National Park Service, NASA or DarkSky International marks to Nyx artwork. A 30-second screen recording and review access through TestFlight are available on request.

The numbers, and where they come from

• 63 national parks, 85 named viewing spots, 18 International Dark Sky Parks (as of July 2026).
• 0 data collected: no server, no analytics, no account. Three public services supply data, each with its own switch.
• Moon rise and set times agree with the U.S. Naval Observatory to within 3.7 minutes at mid-latitude parks and to within a minute at the parks checked in Alaska, Hawaiʻi, American Samoa and the Virgin Islands; sunrise, sunset and twilight to within a minute.
• 903 stars from the Yale Bright Star Catalogue behind every screen.

Data sources and credits

• Weather: Weather data by Open-Meteo.com, licensed CC BY 4.0; averaged over each night's true darkness by Nyx.
• Usual clouds: generated using Copernicus Climate Change Service information [2015–2024], ERA5 (DOI 10.24381/cds.adbb2d47), CC BY 4.0. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains.
• Smoke and haze: Copernicus Atmosphere Monitoring Service (CAMS), via Open-Meteo, CC BY 4.0.
• Sky glow: NASA Black Marble nighttime lights (VNP46A4, DOI 10.5067/VIIRS/VNP46A4.002), public domain; method after Román and others (2018).
• The Moon: NASA's Scientific Visualization Studio (CGI Moon Kit); LRO LROC and LOLA teams.
• Stars: the Yale Bright Star Catalogue, via NASA HEASARC. Star names on Apple Vision Pro: IAU Working Group on Star Names.
• Meteor showers: International Meteor Organization, 2026 Meteor Shower Calendar.
• Lunar eclipses: Eclipse Predictions by Fred Espenak, NASA's GSFC.
• Planets: Paul Schlyter's low-precision orbital elements, computed on the device.
• Parks, alerts and ranger programs: the National Park Service. Starting towns: U.S. Census Bureau, public domain.

Nyx is not affiliated with or endorsed by the National Park Service, NASA or DarkSky International, and no organization named here endorses Nyx.

Sources for this page

1. National Park Service, news release, March 13, 2026: "The National Park Service today announced it recorded more than 323 million recreation visits in 2025." nps.gov. Back
2. Manning, R. and colleagues, night-sky visitor research at Acadia National Park, Park Science, September 2015, as reported by the University of Vermont. uvm.edu. Back

Contact

Hardik Pakhale · harry.pakhale98@gmail.com. Interviews, TestFlight access and further images on request.