At around 9:30pm may 16 2021 we had a crescent moon so i brought out the telescope to look at the moon. while looking at a the moon very close, i think i was using 9mm lense and had a very clear and close view of every detail on the moon. I watched a rectangle shaped ship go from the bottom of the moon that was lit up by the sun and up to the dark part of the moon. The ufo moved very quick and traveled the surface of the moon in about 3 seconds. I also noticed it was fairly bigger than most of the craters on the moon and it left a shading on the ground as it traveled. I came to the conclusion it must have been massive for me to see it as i did. It had the shape of a rectangle if you rounded off its edges and thinned out the front of it.It caught me off guard so i didnt get many detailed on it but it was dark like black or smokey gray.The ufo had no lights nore did it leave a trail. I watched for several hours after that to see it it would come back around se! eing as it moved so fast but never did. I use the telescope alot to take a look at the moon. its a decent telescope and like i said i get really really close detail to the surface and never seen anything pass by the moon like that or that size or even leaving a shadow on the surface. It was pretty interesting. I sometimes see wierd things fly by but you can tell its usually something in our own atmosphere so i kno the difference between the two. Feel free to contact me.