equinox, solstice

The words equinox and solstice refer to four specific days in the year—one in each of the four seasons. In the northern hemisphere, the spring and fall equinoxes occur towards the end of March and September. The summer and winter solstices occur in June and December. These terms are not capitalized.

The word equinox comes from the Latin words aequus (equal) and nox (night). At the equinox, the night is almost equal in length to the day.

• Many tourists visit Stonehenge on the spring and fall equinoxes.

The word solstice comes from the Latin words sol (sun) and stitium (standstill). At the solstice, the sun appears to “stand still” because the position of the sunrise on the horizon changes very little for a few days.

• The summer solstice is the longest day of the year.