I'm very curious to know what they mean when they say the gaps in one of the structures are oriented toward "dusk" and "dawn", as the direction of sun-rise/set

I'm very curious to know what they mean when they say the gaps in one of the structures are oriented toward "dusk" and "dawn", as the direction of sun-rise/set varies about about 90 degrees over the course of the year at that latitude (51N). Given the well-documented astronomical aspects of Stonehenge it wouldn't be a shock if the layout of associated structures also had astronomical significance, but the way it's reported here is more than a little weird.