Select the most appropriate one-word substitution for the given group of words.

The dates when days and nights are of equal length

equinox

The most appropriate one-word substitution for the dates when days and nights are of equal length is equinox.

• Solstice is the time of year when the sun is at its highest or lowest point in the sky.
• Eclipse is the partial or total obscuring of one celestial body by another.
• Stellar is relating to stars.