Astronomy Practice Exam 2025 – Complete Preparation Guide

The event that occurs when the sun is directly above the equator is known as an equinox. During an equinox, which happens two times a year (around March 21 and September 23), day and night are approximately equal in length all over the world. This phenomenon occurs because the tilt of the Earth's axis is such that it is perpendicular to the rays of the sun at those points in the Earth's orbit, leading the sun to shine directly on the equator.

In contrast, a solstice refers to the times of the year when the sun is at its greatest distance from the equator, leading to the longest day (summer solstice) or the longest night (winter solstice). A lunar eclipse occurs when the Earth is positioned directly between the sun and the moon, causing the Earth’s shadow to cover the moon. Perihelion is the point in Earth's orbit where it is closest to the sun, which does not relate to the sun's position above the equator. Thus, the equinox is the correct event associated with the sun being directly above the equator.