A(n) ______ marks the beginning of spring and autumn.

A(n) ______ marks the beginning of spring and autumn.

• A. Solstice
• B. Perihelion
• C. Equinox
• D. Aphelion

Answer: (C)

An equinox marks the moment when the Sun is directly above the Earth’s equator, giving roughly equal day and night lengths. This happens twice a year: the vernal (spring) equinox and the autumnal (fall) equinox, which signal the beginnings of spring and autumn, respectively. The tilt of Earth’s axis means daylight changes as we orbit the Sun, and crossing the equator is what creates that balance of day and night. By contrast, a solstice indicates the longest or shortest day of the year and marks the start of summer or winter, while perihelion and aphelion describe the closest and farthest points in Earth’s orbit from the Sun and don’t define the season starts.

An equinox marks the moment when the Sun is directly above the Earth’s equator, giving roughly equal day and night lengths. This happens twice a year: the vernal (spring) equinox and the autumnal (fall) equinox, which signal the beginnings of spring and autumn, respectively. The tilt of Earth’s axis means daylight changes as we orbit the Sun, and crossing the equator is what creates that balance of day and night. By contrast, a solstice indicates the longest or shortest day of the year and marks the start of summer or winter, while perihelion and aphelion describe the closest and farthest points in Earth’s orbit from the Sun and don’t define the season starts.