We see a few collisions major in the original trilogy. I don't think it necessarily clears anything up. I haven't watched in some years so the details are a little hazy and might be wrong:
In ESB:
- An asteroid collides with a Star Destroyer. Communications with the Star Destroyer are lost, but nothing past the hit is shown on screen. (Presumably shields are active since they're putting these ships in the asteroid field.) [Just to speculate, the asteroid itself might have been pulverized and its materials interfering with communications, or some other shield/asteroid interaction causing loss of communications.]
In ROTJ:
- The Executor loses its shields and the A-wing crashes into the bridge. (No shields.)
- The Executor subsequently loses control and crashes into the Death Star. (No shields.)
And in Rogue One:
- The corvette pushes the two Star Destroyers together and they take major damage. (Unknown shield status.)
In ESB:
- An asteroid collides with a Star Destroyer. Communications with the Star Destroyer are lost, but nothing past the hit is shown on screen. (Presumably shields are active since they're putting these ships in the asteroid field.) [Just to speculate, the asteroid itself might have been pulverized and its materials interfering with communications, or some other shield/asteroid interaction causing loss of communications.]
In ROTJ:
- The Executor loses its shields and the A-wing crashes into the bridge. (No shields.)
- The Executor subsequently loses control and crashes into the Death Star. (No shields.)
And in Rogue One:
- The corvette pushes the two Star Destroyers together and they take major damage. (Unknown shield status.)