There are two days of the year when neither hemisphere is tilted towards or away from the sun. These are the equinoxes:

* Vernal (Spring) Equinox: This occurs around March 20 or 21, when the Sun crosses the celestial equator from south to north.

* Autumnal (Fall) Equinox: This occurs around September 22 or 23, when the Sun crosses the celestial equator from north to south.

On these days, the day and night are approximately equal in length (12 hours each) at all points on Earth.