Question 1

What is Starspots?

Accepted Answer

Starspots is a free, real-time 3D tracker for SpaceX Starlink satellite launches and deployments. It shows you exactly when and where Starlink satellite trains will be visible from your location, using live orbital data from CelesTrak and launch information from Launch Library 2.

Question 2

How can I see Starlink satellites tonight?

Accepted Answer

Open Starspots and set your location using the city search or geolocation. The app will show upcoming visible passes — times when a Starlink deployment train crosses your sky during astronomical twilight while still lit by the Sun. Passes within the next few days of a launch are the brightest and most spectacular, appearing as a string of bright dots moving across the sky.

Question 3

Why can I only see Starlink trains at certain times?

Accepted Answer

Starlink satellites are only visible when they are sunlit but the observer is in darkness — typically during astronomical twilight, roughly 30-90 minutes after sunset or before sunrise. During full night, the satellites are in Earth's shadow and invisible. During the day, they are too faint against the bright sky. Starspots automatically filters for these conditions.

Question 4

What is a Starlink train?

Accepted Answer

A Starlink train is a group of recently launched Starlink satellites that are still close together in orbit, forming a visible string or 'train' of bright objects moving across the sky. Fresh launches (within 7 days) produce the most spectacular trains as the satellites haven't yet spread apart to their final orbital positions.

Question 5

Where does Starspots get its data?

Accepted Answer

Orbital data (TLEs) comes from CelesTrak's Starlink supplemental GP catalog, updated regularly by NORAD. Launch information comes from Launch Library 2 by The Space Devs. All data is free and requires no API keys. The app runs entirely in your browser with no backend server.

Question 6

How accurate are the pass predictions?

Accepted Answer

Pass predictions use SGP4 orbital propagation with real two-line element sets (TLEs) from NORAD via CelesTrak. Accuracy depends on TLE freshness — predictions within a few days of the latest TLE epoch are very accurate. The app also factors in astronomical twilight, satellite sunlight exposure, and Earth's shadow to ensure predicted passes are actually visible to the naked eye.

Question 7

Is Starspots free to use?

Accepted Answer

Yes, completely free. No accounts, no API keys, no usage limits. It works as a progressive web app that you can install on your phone or desktop for offline access.

Question 8

What do the different train colors mean?

Accepted Answer

Fresh Starlink deployment trains (launched within the past 7 days) are shown in vivid colors to highlight the best viewing opportunities. Older trains fade to gray as the satellites spread apart and become harder to see as a distinct group.