The two days of the year on which neither hemisphere is tilted toward or away from the sun are known as the spring and fall ________.

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

Answer: (A)

An equinox is the moment when the Sun is right above the Earth’s equator, so neither hemisphere is tilted toward nor away from the Sun. On these days, day and night are about equal in length, which is why the two days are called spring (vernal) and autumn (fall) equinoxes. The Sun is crossing the celestial equator at these times, not at its highest or lowest point in the sky. In contrast, a solstice is when the Sun is farthest north or south of the equator, producing the longest or shortest day of the year. Eclipses and transits involve alignments with the Moon or the Sun that don’t relate to this tilt-to-the-sun timing.