Final answer:
The time when all locations on Earth experience equal lengths of day and night is during the March Equinox and September Equinox.
Step-by-step explanation:
The time when all locations on Earth experience equal lengths of day and night is during the March Equinox and September Equinox.
During these equinoxes, which occur on about March 21 and September 21, the Sun is on the celestial equator and appears above our planet's equator, favoring neither hemisphere. As a result, every place on Earth receives roughly 12 hours of sunshine and 12 hours of night.