How Twisst works

Twisst is a mashup, combining several data sources to send out the ISS alerts. Here's an explanation of how it all works.

Update: on this page the workings of Twisst are explained as they were at the start of the project. Nowadays, we have our own software to calculate passes and to find timezones.

Infographic: how Twisst gathers and sends out information


  1. First, Twisst asks which twitter users are following the @twisst account and what location these people have entered in their Twitter profile.
  2. Next, these locations are ‘geocoded’. This means Twisst tries to find out what the geographic coordinates are for each location. Google Maps is used for this, or, when Google can't figure out the right coordinates, Yahoo.
  3. When coordinates are found for the Twitter user, Twisst goes to the website to see when ISS will fly over at those coordinates.
  4. To find out what the local time is for the @twisst follower, Twisst asks the geographic database Geonames in which time zone the location is.
  5. So, every time the International Space Station is coming, Twisst sends the follower an alert throught Twitter. It announces when ISS will pass, at the users local time. Also Twisst tells whether it is a remarkable nice one or not - so how bright and how high the space station will be on that pass.


Infographic by O.K. PARKING /

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