The September equinox crosses the seasonal hinge
The Sun crosses Earth's equator moving south, changing the balance of daylight in both hemispheres.
The meaning behind the moment
An equinox is an orbital moment, not a claim that every place receives exactly twelve hours of daylight.
Tilt Earth through the equinox
Tilt the Earth and follow the circle of daylight to see why the two hemispheres trade longer days.
- Start with the physical arrangement.
- Notice what changes from Earth's point of view.
- Connect the geometry to what a person can actually experience.
Useful without a location; richer with one
The global event and indoor experience are complete above. Add a city on This Week for a localized time and an honest easy / possible / not-visible result.
Expectation: online
No single outdoor moment is required. Compare sunrise or sunset positions across several days if you want to see the seasonal change accumulate.
Source, calculation, and revision
- Primary source
- Astronomy Engine validated against USNO
- Last checked
- 2026-08-10T23:00:00+00:00
- Calculation
- astronomy-engine@2.1.19
- Precision
- exact; weather is not included
- Media
- NASA source evidence; Space Now original explainer · original editorial text with linked first-party evidence
We’ll keep this page current
After the event, this durable page will preserve the result, official replay, or a concise correction without silently rewriting the earlier revision.