Which event occurs twice a year and the day and night are approximately equal in length?

Which event occurs twice a year and the day and night are approximately equal in length?

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

Answer: (A)

Twice a year the Sun crosses the celestial equator, so day and night are about the same length. This moment, called an equinox, happens in spring and in autumn. The tilt of Earth’s axis makes most days longer or shorter than nights for the year, but when the Sun is above the equator, sunrise and sunset are roughly 12 hours apart, giving nearly equal day and night. The other options describe events that don’t set day length the same way: a solstice marks the longest or shortest day, an eclipse is a special alignment of Sun, Moon, and Earth, and perihelion is when Earth is closest to the Sun.

Twice a year the Sun crosses the celestial equator, so day and night are about the same length. This moment, called an equinox, happens in spring and in autumn. The tilt of Earth’s axis makes most days longer or shorter than nights for the year, but when the Sun is above the equator, sunrise and sunset are roughly 12 hours apart, giving nearly equal day and night. The other options describe events that don’t set day length the same way: a solstice marks the longest or shortest day, an eclipse is a special alignment of Sun, Moon, and Earth, and perihelion is when Earth is closest to the Sun.