Reference frames
Switch between watching Earth turn and riding with it, and the apparent motion of the sky resolves itself.
For educators
Teach the geometry, not the diagram.
Universal Perspective recomputes positions for any location and moment, so a class can test a prediction instead of accepting an illustration.
Two observers, one instant
Compare two horizons at the same real moment to show that latitude and longitude cause the difference.
Scale honestly
Move from readable spacing to true linear scale and let the emptiness make the point.
Historical timekeeping
Interactive labs rebuild shadow clocks, lunar tallies, and calendars from the same live sky.
What people ask first
- Do students need accounts?
- No. There are no student accounts, no classroom provisioning, and nothing to install.
- Is it scientifically defensible?
- Positions come from published ephemeris models computed in the browser, and the accuracy page states where those models stop being reliable.
- Are the visuals to scale?
- Only where the interface says so. Readable mode deliberately exaggerates body sizes; true scale mode does not.
Run a live demonstration where a class makes a prediction and the real geometry settles it. Open the teaching tools
The sky is doing this right now.
- No student accounts, no classroom sign-up, no install.
- Views that exaggerate size or distance are labelled in the interface.
- The accuracy page states the models used and their limits.