Help under a dark sky.

A full cloud forecast counts for about three days ahead. Further out, a half-filled night is an early look: the forecast is eased toward the park's usual clouds for that month. A hollow night has no forecast yet and uses the usual clouds alone, so its score can change when a forecast arrives. Pull down to refresh when you have a connection, and check that Cloud forecasts is on under Settings → Your privacy.

The four parts add up, then the weakest one can cap the total: heavy cloud, a bright sky glow, smoke or short hours of true darkness. The line under the score names the cap that applies.

Nyx could not get current park alerts. Use the link to the park's current conditions on nps.gov, or contact the park before traveling.

Widen the radius or choose a different starting park. The radius is a straight line, not driving distance.

Tap the starting-park name and choose a park. Location is optional.

Save a park and turn on reminders in Settings. Only nights scoring 90 or more, up to five days ahead and with a recent, full cloud forecast, qualify, and at most one a week for each park. Reminders are recalculated whenever Nyx opens and, when iOS allows, about every six hours in the background.

In Alaska's summer the Sun never sinks 18° below the horizon, so astronomical darkness never arrives. Nyx caps those nights below 40.

Turn it on in Settings or from Control Center. Lower your screen brightness too; Nyx does not change it for you.

Entries and photos stay on your iPhone or iPad. Back up your device with Apple's settings; Nyx has no cloud sync or account recovery. To move a journal to another device, use Export in the Journal tab and open the file on the other device.

In a few US states, the law asks apps to check the age range of new accounts. Where iOS says this applies to your account, it may show its own age range sheet once. Nyx keeps nothing from it and nothing in Nyx depends on the answer.

With the largest accessibility text sizes, Parks shows its search field in the page, under its title, instead of in the navigation bar.

The watch makes no network requests. Its cloud forecasts come from Nyx on your paired iPhone: open Nyx on the iPhone with a connection, and the watch updates. Until then, the watch scores each night with the park's usual clouds and says so.

With the Automatic palette, the watch turns red from dusk to dawn at the park on Tonight. Choose another palette in Nyx on the watch, or use the Red light control.

The watch shows the parks you saved on your iPhone.

Choose a park in the window, then "Stand under this sky". "Leave the sky" closes it. The clock at the bottom of the window steps nights and moves through the hours, and the sky follows.

Nyx on Vision Pro uses the cloud forecast when it has one and each park's usual clouds for the month otherwise (or when you switch forecasts off in Your privacy). For park alerts and field mode, use Nyx on iPhone or iPad.

The sky is computed for the park and night you choose, with south ahead of you, where the Milky Way, Moon and planets cross. It is not turned to your room's real directions, and clouds are not shown. A plaque at your feet says so.

Tap a planet, a bright star, the Moon or the Milky Way core to see its name, its height and its direction. Constellations in the window toolbar shows or hides the figures. Drag across the sky to turn the night by hand.

Open it from the window toolbar. It is lit at that night's phase; drag to turn it, and it turns back to the face we always see.