It wasn't made into a soft circle. The shadow should not be a sharp as seen in that picture you posted. I just softened the edges to make it look less animated and more natural. The first shadow when they are flying over the asteroid surface would also not be detailed. In fact the shape of the falcon would pretty much be as it is given the fact that it's such an uneven surface. If it was flat then the shadow would be more defined, but it isn't. Look at the pic you posted and compare the falcons shadow to every other shadow. That sticks out like a ore thumb as it is too sharp