Question

Days when the Sun’s light hits both hemispheres equally are called __________.

Answer 1

The answer is an equinox 

Answer 2

Days when the Sun’s light hits both hemispheres equally are called equinoxes.   Those are the moments when the Sun is exactly above the equator. These days are called equinox, because the night and day are nearly exactly the same length – 12 hours – all over the world ("equinox," comes from Latin, meaning "equal night).