The full Harvest moon of 16th September 2016 was a bit special.
It coincided with a penumbral eclipse. A lunar eclipse occurs when the full moon lines up with the sun and the Earth, with the Earth’s shadow (umbra) shading the moon. With a penumbral eclipse it is the softer outer shadow of the Earth that is cast over the moon. Rather than a dramatic shadow or a chunk appearing to be taken out of the moon, all that is seen is a slight darkening of the moon.
Of course if it is a cloudy night, as it often is in the UK then you don’t notice anything at all! There will be another chance to see one in February 2017.