Does this really use ChatGPT?

Yes.  Nearly - It uses the OpenAI completion API (GPT3 "Davinci"). It is sent four prompts for every conversation. One to generate the greeting and three more to describe the places. The last three are sent in a single request so as to give it a chance to build up a narrative.

Does ChatGPT really know where satellites are?

No. To figure this out, the public TLEs are gathered from Celestrak. Then using Skyfield the Latitude and Longitude of the satellite for the next few hours are calculated.

To create a set of place names from these, a customised dataset created from the cultural data from Natural Earth Data is used along with GeoPandas to determine the real names of the places the satellite will pass over. These are then sent to the OpenAI API as part of the prompts.

Have the models been trained (fine-tuned) specifically for this?

No. I did not have the time - these are just coming directly from the vanilla API.

Are there any real practical uses for this?

None that I can think of.

Does this cost money?

Yes. OpenAI charges about $0.004 for each "conversation" (which, including prompts comes to about 200 tokens). There's a budget and when it's gone it's gone.