3 spheres, equally spaced apart, moving west to east, all on the same plane and trajectory.

I thought the first one was a falling star and then I realized it was not going to fall. It was on a straight trajectory from west to east and moving faster than anything man made. Then I noticed a second one not far behind it on the same plane and trajectory. And then I saw the third one. They were equally spaced apart and all on the same trajectory. They were white like stars and not in our atmosphere. The sky was clear. They were flying somewhere between 40 and 60 degrees above the horizon line.