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Use this identification decision tree
Use the strongest clue first. Keep the result provisional when the clues disagree.
- It moved smoothly against the stars. If one steady light crossed familiar stars for a minute or longer, call it a possible satellite.
- Several points followed one path. A close-spaced line is a Starlink-like train candidate. A loose group may be ordinary satellites. Neither shape proves a recent launch.
- It flashed or changed brightness repeatedly. Steady red, green, or white position lights plus flashing anti-collision lights suggest an aircraft. A head-on plane can seem slow or nearly still.
- It lasted seconds. One fast streak or brief glowing trail fits a meteor better than a satellite. A meteor can flare once, so a flash alone is not enough.
- It stayed with the star pattern. A planet or star moves with the whole sky. It will not cross a large star pattern in minutes.
- You saw only a flash, or clues conflict. Keep the label uncertain. Record duration, direction, path, color, and whether the light repeated. Do not force a name.
Use brightness and shadow as supporting clues
Satellites reflect sunlight. They can fade when they enter Earth’s shadow.
The ISS can look very bright during a favorable pass. NASA explains that its visibility depends on darkness, sunlight, height, and timing.
Clouds, haze, low elevation, light pollution, satellite attitude, and Earth’s shadow can erase an expected sighting.
Listen for sound after an aircraft passes. Sound arrives late and may not arrive at all.
Treat a line of lights as a conditional clue
Starlink satellites can appear as several points following similar paths. A close-spaced line is often called a train.
That appearance is temporary and depends on each satellite’s orbit and lighting. A dispersed group can look like unrelated satellites.
Do not infer a recent launch from a line of lights. Ground observers cannot confirm a launch date from appearance alone.
Satellites need sunlight to appear bright. You also need a dark enough sky.
Clouds, haze, low elevation, light pollution, satellite attitude, and Earth’s shadow can erase an expected sighting. A prediction is a planning aid, not a guarantee.
Ask whether it blinked regularly, crossed familiar stars in minutes, left a short streak, or matched a current prediction.
Write down the date, local time, direction, height, and any colors. Those details help more than a single photograph.
Use current tools with their limits
Use NASA’s Spot the Station for ISS opportunities. It asks for a location and lists local viewing windows.
NASA explains that some locations have no opportunities. The station may be in daylight, low on the horizon, or in shadow.
Use the ISS guide for station-specific context. For Starlink-like trains, Find Starlink offers third-party location-based predictions.
Find Starlink states that it is not affiliated with SpaceX or Starlink. Treat its result as a prediction.
Compare the direction and time with what you see. SpaceX publishes operational ephemeris information for satellite operators.
This guide does not calculate or promise a local sighting. Current tools can support comparison, but they cannot prove what you saw.
If you remain unsure, keep the label broad. Start with What is that bright star? for quick first triage.
Sources and image credits
- NASA: Spot the Station FAQ. ISS sunlight, Earth-shadow, and local-opportunity limits.
- FAA: Airplane Flying Handbook, aircraft lighting. Aircraft position and anti-collision light patterns.
- NASA: meteors and meteorites. Meteor context.
- ESA: types of orbits. Low-Earth-orbit context only.
- Starlink Space Safety documentation. Operational ephemeris publication.
- Find Starlink. Unaffiliated third-party prediction link. Reviewed on 6 September 2026.
Written for beginners from the sources above. How we research and correct the library. Found an error? Tell us.