Washington Comprehensive Assessment of Science (WCAS) Practice Test

The vernal equinox occurs in the northern hemisphere around March 21-22. This event marks the point in spring when day and night are approximately equal in length. It signifies the start of spring and is an important astronomical event due to the sun's position relative to the equator. During the vernal equinox, the sun crosses the celestial equator, moving from the southern hemisphere to the northern hemisphere, which leads to increased daylight and the warming of temperatures as the season transitions from winter to spring. This timing corresponds closely to various cultural and agricultural calendars that celebrate the arrival of spring and the renewal of life in nature.