Let us begin with the 'hourglass' form of a woman:

... Hourglass also refers to a body shape of women. In this shape bust and hip are significantly large with narrow waist resembling the shape of an hourglass. A common measurement of shape is 36 24 36. The three sizes are the circumferences of bust, waist and hips; usually rendered as three sizes: xx-yy-zz in centimeters or inches ...

If Mother Earth has these proportions, then 24 will immediately be recognized as the measure of her waist (from the tropic of Cancer to the equator there are 24º).

Though today 24º is no longer an exact measure, because the tropical belt is no longer as wide as when the ancient Egyptians once were building their gigantic pyramids:

(Wikipedia)

I suggest 24 once was found to be the correct measure of the waist of Mother Earth.