> A henge can be one of three related types of Neolithic earthwork. The essential characteristic of all three is that they feature a ring-shaped bank and ditch, with the ditch inside the bank. Because the internal ditches would have served defensive purposes poorly, henges are not considered to have been defensive constructions (cf. circular rampart).

https://en.wikipedia.org/wiki/Henge

Celestial alignment has nothing to do with hengeness.