I was hanging laundry on my private roof top, reading a book waiting for my laundry to dry and look up to the next apartment over roof top and see a clear floating UFO just appear out of no where 5 feet above the roof top. I thought it was a balloon for a split second, and waited for it to blow away but it didn’t. UFO Sighting was about the size of basketball, if was clear with metal machinery inside. UFO floated five feet above the apartment for 29 seconds before floating up back to space as a star in the sky. UFO Sighting also changed shape after few hundred feet into the air as a white orb.