I was outside in the backyard taking the dog out, when I noticed an orb of light in the sky, it literally appeared out of nowhere, the sky was black and then it appeared, just a bright glowing orb of solid white light, it came from the west of my location where there is the gulf of mexico.i noticed it immediately because it was larger than any other object in the sky, and it was a solid light, and perfectly sphereical.when i first saw it, and it was moving, i knew it wasnt a star, and it was too big and too close to be a plane. it was only one color solid white light. also the distance it covered in the time it was in the sky was far too fast than ive seen even a jet cover the orb moved a short distance heading east so across the sky it moved west to east for about 5-7 seconds, then turned north im assuming, and i saw the light dim and only a small fraction of the light instead, what appeared to be the top section of the sphere, sort of a crescent of light, maybe 1/5th in size of the total sphere, for only a second or two, and then that fraction of light was gone as well and the sky was black again. now in the second before the sphere became just a fraction crescent of light, it appeared to be 'turning' or changing direction and for some reason it looked almost flat on one side but as it was turning the light shrank into that small crescent, remained for only a second or 2, and then was gone. and then the sky was back to how it was before it had appeared.this wasnt a plane or any known craft that i have seen. there was no sound when it appeared or the entire time it was moving. there were also at least one other craft in the sky, but it was a plane that looked to be a few miles east of where it appeared and that one for sure and i could tell the difference because the planes had the flashing white and red lights. the sphere i saw did not flash, or pulse at all and the light itself was larger than any object in the sky at the time, except for the moon. in proportion to the moon it was maybe 1/4th the size of the moon. and it was a perfect circle and looked like a sphere although it could be cylindrical because i only saw the circle of light. it wasnt in the air long enough for me to even take a picture or tell anyone to come look at it, it was just there, and as i watched wondering if it was a UFO it was gone. i had never seen something like that which had made me want to report it but what i saw in this incident just felt like something nobody would believe but i wanted to report it anyway.