Last night a whirring noise started coming from the engine above the normal engine sound. This morning the car was dead. The battery was good. Could this be the alternator? If not, what else could it be?
When you say the car was dead what exactly do you mean? Was it turning over at all but not firing or was there absolutely nothing happening when you turned the key. If the battery is charged then the starter motor should turn. The alternator is spun by the engine which in turn charges the battery. If the battery is charged then it doesn't sound like the alternator is dud.