NyxiPad
The score beside its full breakdown in wide windows, any orientation, a park in its own window, and parks or nights you can drag onto Plan or the journal.
Free for iPhone, iPad, Apple Watch and Vision Pro
Find where and when the sky is darkest.
Nyx gives every night a darkness score from 0 to 100, from the Moon, the clouds, the glow of nearby towns and the hours of full darkness. It covers the 63 US national parks, about 3,400 dark places in 172 countries, and any place you save. It also shows why.
On the App Store in every country except mainland China and the European Union.
- Free, no in-app purchases
- No account, no ads
- Works offline
- Data Not Collected
The darkness score
One number, with its reasons.
Four things decide whether you will see the Milky Way. Nyx adds them up for each place and night, then lets the weakest one hold the total down, because one problem is enough to spoil a night.
- Moonlight40 / 40
How much moonlight reaches the sky through the hours of true darkness, by the Moon's phase and height.
- Clouds25 / 25
Averaged over the hours of true darkness only. At the US national parks, three weather models are compared for the coming week.
- Sky glow17 / 20
How bright the sky is from the glow of nearby towns, on the Bortle scale from 1 (darkest) to 9 (city sky): an estimate, with satellite night lights to show where the glow comes from.
- True darkness15 / 15
Hours with the Sun 18° below the horizon. In an Alaskan summer there are none, and Nyx says so.
The weakest part can cap the rest. A bright Moon, heavy cloud, a bright sky, wildfire smoke or a short night holds the score down, and Nyx names the cap under the number: "Clouds limit tonight to 55." An overcast night never reads as good.
Score bands:
- Poorbelow 40
- Fair40 and up
- Good60 and up
- Excellent75 and up
- Pristine90 and up
Tonight
The darkest sky near you.
Start from where you are, from any of more than 31,500 towns and cities, from a park, or from a spot you saved. Nyx shows the best-scoring places around it tonight, with the reasons on the same screen.
- A distance you choose, measured as a straight line on the map, not by road: "within 200 mi (320 km) in a straight line".
- At the US national parks, National Park Service alerts sit beside the score; a dark sky does not help if the road is closed. Elsewhere Nyx says plainly that it cannot check closures, and links the park's own site.
- From your starting point, Nyx also works out tonight's Moon, darkness and planets, without asking any service.
The park, in three chapters
Tonight. The sky. The place.
Each park's page reads in three chapters: tonight's score and its best window, the sky and what is in it, and the place itself, with viewing spots, sky glow and where to stay.
- Tonight's sky, full screen: drag to turn, slide from sunset to sunrise, and see where the Milky Way stands before you drive, with the brightest stars named.
- "Before you go" gathers the park's alerts. Campgrounds link only to Recreation.gov or nps.gov.
What's up tonight
The Milky Way, and when to look.
The bright center of the Milky Way (its core) and when it is up at the park you chose, the planets with where and when they rise, meteor showers with an honest rate range, zodiacal light (a faint glow from dust along the Sun's path), satellites, and lunar eclipses the park can actually see.
- Computed on your iPhone. Planets are placed to about a degree through 2032.
- Times are park-local, wherever you plan from.
Plan
Choose the best night to go.
The best nights in reach over the next 30, one for each place. A month for one park, each night a small sky sized by its score, with the best five nights in a row circled. Or tell Nyx which nights you are free, and it suggests a park for each.
A forecast is reliable for a few days. After that Nyx uses each park's usual clouds for that month, so every night shows which it is:
- Full forecast
- Early look
- No cloud forecast yet
Every park tonight
The US parks, and the world.
The Parks tab draws all 63 US national parks by tonight's score, from Acadia to American Samoa, with closures marked. Around the world, places are grouped by country, with a world map. Tap a place to open it, or switch to the list.
- Drawn on the device over a plain outline of the country, or of the world from Natural Earth. No map service learns where you look.
- Filled, half and hollow marks tell forecast nights from usual-cloud nights here too.
- Start from a town abroad, as in the first screen from Ishigaki in Japan, or save a spot of your own, as in the second.
Field mode
At the park, the screen turns red.
Your eyes need twenty to thirty minutes to adapt to the dark, and one glance at a bright screen undoes much of it. Field mode dims everything to deep red, counts down to true darkness and shows the part of the sky you point the phone at, without using the camera.
- A dark-adaptation clock, alarms for true darkness and the core, and a Live Activity that follows the night from your Lock Screen.
- Where to look by sound: a tone placed around you leads you toward the core, and follows your head with headphones that track movement.
- Red text stays easy to read: its contrast on black is 6.9 to 1 (a brighter red reaches 7.8 to 1), and at least 4.5 to 1 for red-blind and green-blind eyes. Accessibility guidelines ask for 4.5 to 1.
Journal
Every night becomes a star.
A private journal turns each night you go out into a star in your own constellation, and gathers your year under the stars. Add a night by voice with Siri, describe your photos, and export the journal as a file you keep.
- Notes and photos stay on your device. Nyx has no account and no cloud sync.
For more people
Hear the night. Feel the Moon.
Every custom control in Nyx speaks a summary of its data. "Listen to tonight" plays the shape of the night as tones, with a transcript, and "Feel tonight" plays it as touch. Audio graphs let VoiceOver users hear a month of darkness.
- Designed for VoiceOver and the largest text sizes, with night vision for night-adapted eyes and a one-answer layout for Assistive Access.
- Step-free notes for viewing spots, quoted from the park's own accessibility page where it says something, and marked unknown where it does not.
- City glow named: satellite night lights show which towns brighten each park's horizon, and how much of the light lies in each direction.
New in 2.10
The night itself, on the dial.
Nyx 2.10 is a free update. The dial draws the night from sunset to sunrise, every screen names the same best night, and night vision can turn on by itself at dusk.
The dial is the night
It runs from sunset to sunrise, with true darkness and the best hours drawn brightest and the score in the middle. When the best hours fall under a bright Moon, Nyx says so rather than drawing them as dark sky.
Step through two weeks
Drag sideways across Tonight's dial to step through the next two weeks: the darkest place in reach and its score follow your finger. VoiceOver steps night by night.
Night vision at dusk
Night vision can turn on at civil dusk where you plan from and off at dawn, at the same minute on iPhone and Apple Watch, only while Nyx is open. Night vision's red now reads for red-blind and green-blind eyes too.
The Little Dipper count
Each park in the list shows how many of the Little Dipper's seven stars you would likely see, an estimate from its sky glow, the Moon and the air. It is not part of the score.
Around the world
The darkest nights, wherever you are.
Nyx looks for the darkest nights around the world. The 63 US national parks are still the main focus, checked by hand.
Around the world
About 3,400 national parks and certified dark-sky places in 172 countries, each scored night by night. Sky brightness and usual clouds are labeled as estimates, and a place abroad says plainly that Nyx cannot check its closures.
Start anywhere
Any of more than 31,500 towns and cities as your starting point, or a spot of your own: where you stand, a pair of coordinates or a town. Spots are scored and followed like parks.
Private by region
Forecasts for places abroad are asked for by whole regions, about the size of a country. A spot you save is sent only rounded to about 11 km (7 miles), behind its own switch.
A closer look at the sky
The Moon in relief from NASA's elevation data, tonight's sky with the brightest stars named, and the forecast models' range on the dial when they disagree.
In five languages
English, Spanish, German, French and Japanese. The translations are drafts; native speakers will review each one, and their corrections follow in updates. The App Store does not offer Nyx in the European Union yet.
On every device
The same sky, wherever you look.
Apple Watch
Tonight's score on your wrist, the Digital Crown to look a week ahead, the forecast models' range when they differ, a dark-adaptation clock that taps when your eyes are ready, and a face that turns red at dusk.
Apple Vision Pro
Stand under a US national park's computed sky on the night you choose, with the forecast's clouds. Tap a star for its name, turn the night by hand, and set the Moon, lit at its true phase, on your table.
The Moon on your table
On Apple Vision Pro, the Moon in NASA's color and relief, lit from the Sun's true direction for the night you pick, so its shadow line crosses craters as the phase turns.
Around the system
- Tonight and Moon widgets for the Home Screen, Lock Screen and StandBy; step the Tonight widget through the week.
- On iPhone Duo, two columns across the inner display that meet at the fold.
- Control Center controls for night vision and field mode.
- Follow a night: a Live Activity that starts itself before sunset.
- Ask Siri for the darkness score, or record a night in your journal.
- Pick up a park on another of your devices with Handoff.
Honest by design
It says what it cannot know.
A planning app is only useful if you can trust it, so Nyx draws its uncertainty instead of hiding it.
Models side by side
At the US national parks, three weather models are compared for the next week. When they disagree, Nyx draws the range and says so.
Usual clouds, labeled
Beyond about three days, the forecast slowly changes to each park's usual clouds for the month, from ten years of climate records, and those nights are marked.
Estimates called estimates
Bortle classes, sky glow and meteor rates are all labeled as estimates. Moonrise agrees with the U.S. Naval Observatory to within minutes.
Access first
A high score never means a road is open. At the US national parks, closures sit beside the number, and if alerts can't load, Nyx says so and links to the park's current conditions. Elsewhere it says it cannot check closures.
Privacy
Your journal, photos and exact location stay on your device.
No account, no ads, no analytics, no tracking. The astronomy runs on your device, so the Moon, twilight and the Milky Way work offline. Your journal never leaves your device.
This website is the same: no cookies, no scripts, no analytics.
App Store privacy label
Data Not Collected
Nyx asks four public services for data, and each has its own switch in Nyx, under Settings → Your privacy:
api.open-meteo.comCloud forecasts: for the 63 US parks by their public coordinates, with the cloud layers above Haleakalā's summit, for places abroad by whole regions, and for spots you save rounded to about 11 km (7 miles). Never where you are, unless you save it as a spotair-quality-api.open-meteo.comSmoke and haze forecasts: for the 63 US parks by their public coordinates, and for places abroad by the same whole regions as their clouds. Never for your spotsdeveloper.nps.govPark alerts and campgrounds for all 63 US parks, and ranger night-sky programs for the park you openservices.swpc.noaa.govNOAA's aurora forecast: one file for the whole world, at most every three hours, naming no place
Plan a darker night.
Free, with no subscriptions or in-app purchases. For iPhone and iPad with iOS 26 or later, Apple Watch, and Apple Vision Pro.
On the App Store in every country except mainland China and the European Union.
Every number in the screens comes from the app's own engine and real forecasts on October 11, 2026. The sky screen shows a chosen summer night; the journal and the saved spot use samples.