Correct Option
The correct option isThroughout the whole Earth.
Explanation
An Equinox occurs when the Sun is vertically overhead at the Equator. This phenomenon happens twice a year, approximately on March 21 (Vernal Equinox) and September 23 (Autumnal Equinox).
Detailed Analysis
- Position of the Sun: During an equinox, the Earth's axis is inclined neither towards nor away from the Sun. The Sun's rays fall vertically on the Equator.
- Circle of Illumination: The circle of illumination (the great circle dividing day and night) passes directly through both the North and South Poles.
- Global Effect: Because the circle of illumination bisects all parallels of latitude exactly in half, every place on Earth experiences roughly 12 hours of daylight and 12 hours of darkness.
- Exceptions: While theoretically equal, atmospheric refraction can cause the day to appear slightly longer than the night, but conceptually, the duration is considered equal across the globe.
Key Takeaway: During an Equinox, the circle of illumination passes through the poles, resulting in equal duration of day and night throughout the whole Earth.