Grand Moff Tarkin could have easily showed the Deathstar power by just destroying alderaan capital. i know what happened in a new hope is set in stone already but this is a question that comes to mind. Thanks to rogue one we now know the Deathstar lazer can do more then just bow up a plant, it can be used just to destroy a rebelling city.

So did why didn't Grand Moff Tarkin just have the deathstar fire a shot at alderaan capital it would have driven fear into the populous of the planet and it would not have push so many planets to join the rebel alliance.
