Autumnal blot – first possible day

On the autumnal blot the shadow of the higher stone passes across the lower stone 3.2m away, allowing the shadow to just reach the top of the lower stone.

The animation shows the autumnal blot based on the autumnal equinox as defined by 1) Height Model Equinox and 2) Refraction Equinox. See definitions in Days-of-the-calendar.

The gradients of the top of the stones are in good alignment with the sun’s path.

The shadows movement across the stone is correct based on 6st October 645, exactly a half moon cycle after the autumnal equinox, defined as the day after autumnal equinox according to today’s definition. That is to say the day when day and night are of equal length under the influence of sunlight’s refraction in earth’s atmosphere (“refraction equinox”).

Visibility today

Leaves and branches of a tree partially obscures the sun which makes the shadow less clear. I have not had the opportunity to see if the shadow is sufficiently clear to be seen. The next opportunity is on 6th October 2014, between 17:00 and 17:30.