I saw a crescent or boomerang shaped UFO that seemed to move at such speed it appeared to shrink down to nothing, glowing in the night

I saw a boomerang shaped or upside down crescent moon shaped UFO that seemed to move at such speed it appeared to shrink down to nothing, glowing in the night. I watched as it seemingly shrunken down from the size of a small crescent moon to absolutely nothing. it looked like it wasn't too high in the sky and maybe a mile from where I was running but it was early and dark so I was the only one to see it. I can assure you the way it moved was unlike anything I've ever seen before. And even they way it glowed was odd. I am 18 years old and this is not a hoax.