Small bright dot hovering in an unusual way with green aura being emitted and changing in size

Object appeared in the sky to the east of Bridge of Allan in Stirling, Scotland. It appeared to hover around for about forty minutes then disappeared temporarily. It came back into view and appeared to be moving southeast, in the direction of Falkirk.
During this time it appeared to suddenly change diameter and appeared as a green sphere. It switched suddenly between the green large diameter state and a single spot of light.
Some footage was shot through a window but I confirmed it was not an optical effect caused by the window previously, and the earlier videos were shot with the phone outside of the window. Some videos could not be uploaded due to file size but please email me if interested.