if you measure how long the star disappears and you know how fast the object was moving, you have just directly measured the size of the object. if you live in an old farmhouse you know that your cold may seep throughout the walls and the old house windows. all journey details and options on how you want your trip to be are presented for you to choose what suits you best. it is also important to pivot with accuracy so the seam line will be correct on both sides of the corner. and how do you want me to hit it? 