How Orbit calculates your sky

Orbit uses your selected location, date, and time to calculate where supported objects appear from your observing position. Planet and Moon positions use Astronomy Engine calculations; deep-sky targets use catalog coordinates transformed to your local sky.

Altitude tells you how high an object is above the horizon. Azimuth and compass direction tell you where to look.

Data sources

Time & time zones

Visible Objects, rise/set times, and planning labels are calculated for the selected instant and displayed in the device’s local time zone. When a future time is selected, Orbit changes labels from “now” to “selected time” so planned observations are not mistaken for current conditions.

Tonight’s Top Picks

Orbit ranks the best things to look at over the next 12 hours. It weighs how high each object gets, how dark the sky is, how much the Moon gets in the way, how bright the object is, your observing mode and equipment, and the weather forecast when it's available. Objects low on the horizon score poorly; objects near their highest point score well.

Each pick comes with its best viewing window and a short reason it ranked where it did. If the forecast isn't available or you're offline, picks are based on astronomy alone.

Scores are held back when weather or sky-darkness information is missing, so 100/100 only happens with clear skies, full darkness, no Moon in the way and a very dark site. Sky darkness for your location is coming soon.

Observing difficulty

Orbit translates magnitude and target type into practical guidance: Naked Eye, Binoculars, Small Telescope, Medium Telescope, Large Telescope, or Imaging Recommended. For extended objects such as galaxies and nebulae, integrated magnitude alone can be misleading, so Orbit also applies a difficulty penalty for diffuse targets, large apparent size, low altitude, and bright Moon conditions.

These ratings are guidance rather than hard aperture limits. Telescope quality, sky darkness, transparency, magnification, observer experience, and local light pollution all matter.

Accuracy & limitations

Orbit's calculations are checked against NASA/JPL Horizons every hour by the Accuracy Lab on Orbit's website. The Sun, Moon and planets are checked from Pennsylvania and from ten places around the world, and tracked comets are checked in rotation. Deep-sky positions are checked against the SIMBAD catalog. The results are published live.

Open the Accuracy Lab

Actual visibility can differ because of clouds, haze, light pollution, buildings, trees, terrain, atmospheric refraction, and device-location accuracy. Comet brightness is an estimate.

Location & privacy

Orbit uses location for local-sky calculations, which run on your device, and does not require an Orbit account. Some features need a server, and for those Orbit sends your location rounded to about 1 km, never the exact point: the weather forecast (Open-Meteo, or Orbit's backup weather service if Open-Meteo can't be reached), the time zone for typed coordinates (Open-Meteo), and the hourly comet accuracy check (Orbit's Accuracy Lab, which asks NASA/JPL Horizons and stores nothing). When you search for a place, the text you type is sent to Open-Meteo's place search. Avoid including private information in beta feedback.

Read the full privacy policy

Sky Map Navigation

The sky map shows all 88 constellations, with their stars, lines and names placed from catalog coordinates. Names move aside when they would overlap. The figures follow the Stellarium catalog, so a few, like Vulpecula, are only a line or two.

Night Explorer opens the map full screen, with layers you can turn on and off, including the Milky Way. Tap any object for its details.

Night Planner

Build My Night, under Plan, turns your session into an ordered observing timeline. Choose how long you have, what you want to see and what equipment you're using. Orbit then schedules targets by altitude, darkness, the Moon, the weather when it's available and how well each target suits your equipment.

Objects saved to My Sky get priority when they're still a good fit. If dawn or daylight cuts the session short, Orbit tells you, and it leaves a gap empty rather than filling it with weak targets.

Installing Orbit

Orbit is a web app you can add to your home screen, where it opens like any other app and keeps working offline. If Chrome doesn't offer a one-tap install, Orbit shows the Add to Home Screen steps instead. On iPhone, use Safari's Share button and choose Add to Home Screen.

Weather

Hourly forecasts (cloud cover by layer, precipitation chance, temperature, dew point, wind and visibility) are weather data by Open-Meteo.com, licensed CC BY 4.0. If it can't be reached, Orbit falls back to current conditions only and plans on astronomy alone.

Website & support

Orbit lives at orbitskyobserver.com, where you can see the live Accuracy Lab and support Orbit to keep it free and ad-free.

Help improve Orbit

Report a problem, suggest a feature, or send general feedback. Orbit adds its version and device/browser information to help reproduce beta issues.