How this works, and how well — sources, licence, measured numbers
What this is, and what it is not
Every name on the map is a person listed as currently in space by Launch Library 2. Each station's position is computed in your browser from its public orbital elements (SGP4, the standard model for this) and redrawn about twenty times a second. Footprints are placed along the last 94 minutes of each station's track and stay where they fell; the dotted line ahead is the next 94 minutes. The shaded night follows the real Sun.
- Everyone aboard a station is in the same place. The parallel lanes of footprints are decoration, so that eleven walkers can be told apart.
- Which station someone is on is inferred from their agency: CNSA astronauts to Tiangong, everyone else to the ISS. Launch Library's expedition rosters lag launches by days, so they were not used. Anyone who launched in the last day is flagged, since they may still be on the way up.
- "Overhead" means above 10° elevation from your rough location. It says nothing about whether the station is sunlit or visible.
- Your rough location comes from a city-level IP lookup (ipwho.is, with geojs.io and ipinfo.io as fallbacks), rounded to 0.1° and kept in this browser for a day. IP lookups are often wrong by a city or more, so the page also offers your device's location, which is rounded the same way and kept for 30 days. Neither is sent to this site.
- This is a toy. Do not use it to schedule anything that matters.
Measured
| ISS position vs wheretheiss.at, same instant | 0.6 km mean, 0.7 km max over ten instants spanning 4.5 hours; altitude within 0.04 km. wheretheiss.at starts from the same public elements, so this checks the code, not the elements |
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| Sub-solar point vs wheretheiss.at | Within 0.001° in latitude and longitude over the same ten instants |
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| Orbital elements | Fetched at most every 3 hours (CelesTrak asks for two). Accuracy falls as elements age; the status line shows their age and turns red after a week |
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| Crew list | Cached 6 hours (Launch Library allows 15 anonymous requests an hour); an embedded snapshot of 2026-10-04 is used if both the live call and the cache fail, and the page says so |
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Credits and licence
Crew: Launch Library 2 by The Space Devs. Orbital elements: CelesTrak (Dr. T.S. Kelso). Propagation: satellite.js (MIT). Coastlines and borders: Natural Earth (public domain) via world-atlas. Rough location: ipwho.is. Cross-check: Where is the ISS at? Typefaces: IM Fell and Uncial Antiqua, from Google Fonts (SIL OFL). Page code: Apache-2.0, as the rest of this repository. Your browser talks to these services directly; nothing is sent to this site. The Marauder's Map belongs to the world of Harry Potter; this is an unaffiliated tribute.