How the checks work

Everything on a case page can be traced back to a public dataset and a line of arithmetic.

The Sky Snapshot

Every report freezes a ±15-minute window around the time you gave, at the location you gave (rounded to about a kilometer in public). For that window we compute:

• Sun, Moon and bright planets with astronomy-engine, including twilight state and the Moon's phase.
• Satellite passes by propagating orbital elements (Space-Track.org when credentials are present, otherwise CelesTrak) with SGP4 via satellite.js. A pass counts as visible only when the satellite is sunlit while your sky is dark. We check the stations, the brightest large objects, and everything launched in the last 30 days (for Starlink trains).
• Launches within 90 minutes and 2,500 km from Launch Library 2, with a twilight test for the glowing plume.
• Space weather (planetary Kp) from NOAA SWPC or GFZ Potsdam, for aurora.
• Weather at the nearest station (NOAA NWS in the US, Open-Meteo elsewhere): cloud cover, visibility, wind.
• Meteor showers active that night.
• Aircraft near you, from adsb.lol, when the report is filed within minutes of the sighting. Historical replay is coming.

Scoring

Each candidate explanation starts from a base rate and gains or loses points for every detail you gave and every record we found. Points are listed on the case page with their reasons. 80% or more is Likely, 50–79% is Possible, below 50% is Doesn't fit. If nothing reaches 50%, the case is Still unexplained, and it stays that way until new information changes the numbers.

The AI first look

The "Sky Investigator" reply on each case is written by a language model from the scored candidates. It cannot add a candidate the engine did not score or claim more confidence than the engine gave; replies that try are discarded and replaced with a plain template. Rate it; the ratings feed back into how we prompt it.

Limits

Orbit elements go stale after a few days, so passes for reports older than two weeks are not computed yet (historical element sets are on the roadmap). Military aircraft, many small aircraft and most drones do not broadcast their position. A location rounded to a kilometer and a time rounded to a minute are plenty for everything except very low, very close objects.