Binary star system

 

This gate at Rydal reminded me of an eclipsing binary star system. The two stars would orbit each other. When side by side we see the brightness of both of them. When one then passes in front of the other, we only see the brightness of the front star. What we would then notice in practice is what seems to be a star that gets first brighter and then dimmer, then brighter, then dimmer. Inspection with a telescope at the bright part of the cycle would reveal two stars and the time period can be worked out from the cycle of bright and dim.