I saw the same thing twice on my way into work around 630am before we set the clocks back, so it was still dark but closer to twilight in the morning. Same thing, I was driving on 95N when I saw something really bright appear in the sky. It appeared to move to the Northeast, and I thought it was a plane heading towards Logan. To my surprise it dimmed out and totally vanished.

My thoughts were it was a satellite at an angle at that given time that was reflecting quite a bit of sunlight. It must have moved in such a way that caused it to brighten, and darken from our perspective.

I’ve seen the ISS suddenly dim as it is passing over. It behaved the same way.