My Dear Satellite: ISS Tracker

Once you know that the bright point drifting across the night sky is the International Space Station, looking up changes a little.

■ Where it is right now
The Space Station's position, given not as a dot on a map but as a direction and an angle from where you stand. Orbital elements come from Celestrak and the SGP4 model runs on your device, so the calculation happens locally rather than on a server.

■ When you can see it
Five days of passes over the city you choose, with the ones you can actually see marked separately: those are the passes where the sky is already dark while sunlight still reaches the station. You get the direction it rises from, how high it climbs, and how long it stays visible.

■ Satellite catalogue
Ten satellites, including the Space Station, Hubble and James Webb, and Korean spacecraft such as Danuri, Chollian, Arirang and NEXTSat-2. NORAD numbers and orbital data are exactly as registered in Celestrak, with a written account of what each one actually does.

■ Earth diary
The daylit face of Earth, photographed by DSCOVR from 1.5 million km away and fetched from NASA EPIC. You can also see who is in space right now.

■ Observation notes
Keep the satellites you like and write down when and where you saw them. Notes stay on your device.

■ No location permission required
You pick your viewing point from a list of 12 cities in South Korea instead.

12 languages, selectable inside the app.

Data sources: Celestrak (orbital elements), NASA EPIC (Earth imagery), NOAA SWPC (geomagnetic index)

Recent changes:
New look: your sky now sits in an observation window over a night-sky photo, and visible passes for the next five days come first. Each catalogue card shows how far the satellite is from Earth. Fixed line breaks in long labels, the English date format, and the white flash at launch.