equinoxes

Example:The spring equinox usually falls on March 20 or 21, and it marks the beginning of spring in the Northern Hemisphere.

Definition:The time of the year when the sun crosses the celestial equator, around March 20 or 21. During this time, day and night are nearly equal in length.

Example:The autumnal equinox, typically occurring on September 22 or 23, marks the start of fall in the Northern Hemisphere.

Definition:The time of the year when the sun crosses the celestial equator heading south, around September 22 or 23. During this time, day and night are nearly equal in length.

Example:The vernal equinox is significant for determining the start of spring and for astronomical observations.

Definition:Another term for the spring equinox, referring to the point in time when the sun crosses the celestial equator moving northward.