About this site and how we compute it
Satellites Tonight answers one question: can I see Starlink tonight from my city? Every number on the site is computed from public orbit data. Nothing is guessed by hand.
Data
- Orbits: CelesTrak. For predictions we use the SupGP Starlink file, built from the ephemerides SpaceX publishes for its satellites, which is more accurate than catalog element sets for new launches. For any launch SupGP does not cover we fall back to CelesTrak's GP element sets. We download each file at most once every 2 hours (our schedule is every 6) and cache it.
- Launch dates, re-entries, status: the CelesTrak satellite catalog (SATCAT), refreshed daily.
- Cities: coordinates, time zones and populations from GeoNames (CC BY 4.0); US metro areas from the Census Bureau's Vintage 2024 estimates. We list 1,075 cities: every US city above 100,000 people, the main city of every US metro area above 100,000 and every state capital, plus the largest cities of Australia, Bahamas, Canada, Ghana, India, Ireland, Jamaica, Kenya, Malta, New Zealand, Nigeria, Philippines, Singapore, South Africa, Trinidad and Tobago, United Kingdom.
Which satellites we predict
Only those you can reasonably see: satellites from launches in the last 10 days (the train), plus satellites launched in the last 30 days that are still below 420 km while they raise their orbits. Starlink satellites at their working altitude are about magnitude 6–7 after SpaceX's brightness mitigation, too faint for most observers, so listing hundreds of them each night would not help anyone. That is the main reason a city page can say "No".
Currently used (7 Oct 2026, 16:02 UTC): 53 satellites from 2 launches.
| Launch | Date | Age | Group | Used | Altitude | Orbit source |
|---|---|---|---|---|---|---|
| 2026-225 | 2026-09-28 | 9 d | train | 26/26 | 296–315 km | SupGP |
| 2026-219 | 2026-09-20 | 17 d | raising | 27/27 | 338–366 km | SupGP |
How a pass is found
- Positions are computed with SGP4 (via Skyfield's sgp4 library) every 20 seconds for the next 9 days, and rotated into Earth-fixed coordinates with Skyfield. The Sun's position comes from the JPL DE440s ephemeris.
- A moment counts as visible from a city when the Sun is more than 6° below the horizon there (civil twilight is over), the satellite is outside Earth's shadow, and the satellite is at least 10° above the horizon.
- Consecutive visible moments form a pass. Start and end times where the 10° limit applies are interpolated; the highest point is refined with a parabola. Times are shown in the city's local time zone, rounded to the minute.
- Passes from the same launch that start within 5 minutes of each other are shown as one group. If the launch is under 10 days old, the group is labelled a train.
Brightness (approximate)
Brightness depends on each satellite's attitude toward the Sun, which is not public, so we give an estimate, not a measurement: magnitude = M + 5·log10(distance / 1,000 km) + 0.01 × (phase angle − 90°), with M = 5.0 for train satellites and 5.7 for older ones still raising their orbits. These are in line with published photometry of Starlink satellites in their orbit-raising phase. The result is rounded to half a magnitude, and passes estimated fainter than magnitude 5 are not listed. Treat it as ±1 magnitude.
Accuracy
On 6 October 2026 we compared our predictions for one satellite of the 20 September 2026 launch (STARLINK-38438) with findstarlink.com's public page for London, Anchorage and Cairns. Both sites use SpaceX's published ephemerides but different software. All 12 passes listed by both sites started within one minute of each other, with start and peak heights within 4 degrees and directions within one compass point; for Cairns both sites found no passes of that satellite. Our brightness estimates were 0.5 to 1.4 magnitudes fainter than theirs, so treat our magnitudes as cautious.
Satellites still raising their orbits fire their thrusters often, so their predictions drift: we refresh every 6 hours, and you should check again shortly before going out.
What we do not do
- No weather forecast: a "Yes" assumes a clear sky.
- No Event markup: a satellite pass is not an event someone organises, so we do not mark it up as one.
- No data from SpaceX's operator-only systems.
Who runs it
Satellites Tonight is an independent site. Not affiliated with SpaceX or Starlink. Starlink is a trademark of SpaceX. The site is generated by software from the sources above; corrections to city coordinates are welcome.