I spotted what I thought was a star but it was moving.

I was looking into the night sky over Boston Harbor and Logan Airport.
I spotted a bright light at a high altitude that I first thought was a star but I realized it was moving in West/Northwesterly direction over Boston Harbor just south of Logan Airport. I took a photograph of the object with my IPhone. When I zoomed in/enlarged the image it appeared to be a white rocket with two side booster rockets attached, one blue, the other red. There were no lights flashing on the three cylinders, nor any visible exhaust coming from any of them. The object moved slowly and steadily in a straight line from southwest to northeast and disappeared from view as it passed over tall buildings in downtown Boston. I wonder if it is a SpaceX rocket or a rocket connected to the international space station or a rocket used to launch a military, research or commercial satellite.