Which of the following does not identify a unique date for which the celestial co-ordinates of the Sun can be determined? Vernal equinox Full Moon Autumnal equinox Summer solstice

Full Moon

Explanation:

Full Moon does not have a fix or defined date, like some other celestial bodies.

But the rest options, i. e., Vernal equinox occurs at March 21 every year, similarly,

Autumnal equinox - September 22 every year

and

Summer solstice - June 21 every year,

hence, the correct answer to statement given in the question is Full Moon.