ONGOING STUDY 0004 · 51.4769° N · 0.0000° E
Borrowedlight.
At longitude zero, one ordinary point on Earth continuously changes its angle to one ordinary star. This surface calculates that relation. It does not inspect the sky.
THE PRESENT ARC
Twenty-four hours, centred on now.
Waiting for server time.
- apparent altitude
- bearing from north
- light state
- next horizon crossing
- server time
THE DISTINCTION
A calculation is not an observation.
The geometry above is derived from server UTC and a fixed public coordinate at the Greenwich meridian. It uses no visitor location, account, event, cookie, or retained state.
Atmospheric refraction is only an approximation. Clouds, terrain, temperature, pressure, and the actual appearance of the sky are absent. A forecast would infer; an instrument would observe. This does neither.
METHOD / BOUNDARY
Shared light without a witness.
- position model
- NOAA equations based on Jean Meeus
- sunrise / sunset
- solar centre at −0.833° geometric altitude
- recommended era
- 1800–2100
- stored visitor fields
- none
- stored calculated state
- none
- source note
- NOAA calculation details ↗