Bright light in the sky vanishes in seconds

I walked out into my back yard and looked up at the sky, looking east. There is nothing obscuring vision here such as trees, buildings, walls, or lights.
 There was a noticeably bright light in the sky, not directly overhead, but probably at low-flying plane altitude.
 It was round and white. Not flashing. It was standing still. My first thought was a plane moving towards me, but it was not blinking. It looked brighter than a planet.
 After around 5 seconds, it slowly moved North and gradually became dimmer until it only looked like a distant star. This went on for about 10 seconds before it disappeared completely.
 Skywatching is a hobby of mine and I have excellent vision, even at night. I have seen hundreds of planes, and this was not one. There was no visible plane body, nor were there blinking lights.
 At that altitude, I should have been able to clearly read the words "UPS" or "AMAZON" if it were a plane. If it were at a higher altitude, it would need to be tremendously bright. Even then, planes at ~20,000 still blink.
 There was actually an airplane nearby at the same time. The plane looked as a normal plane should...with blinking lights and a visible body, making a distant sound as it moved. It was farther away, moving sort of South-West.
 If I put my hand up to the sky, it was probably about a finger's length below the UFO and slightly to the right of it. It was very easy to see the difference between the crafts.
 Weird things are seen here quite often and my family and I have reported crafts in this area before. We have photos and video of others, but not this one.