Why did my car window explode?

• This evening, I got home from work and came inside. About twenty minutes later, my daughter came in from playing in the backyard, crying, and told me that my car window had broken. When I went out, it became clear that the window had burst from the inside--the bits of glass still attached were bowed outward, and 80% of the fallen glass was in the driveway. What on earth happened? More information, maybe relevant. The car in question is a 2004 Saturn. The car was locked, and there weren't any--you know, huge, window-breaking birds inside of it.The window had no scratches, nor had it been hit by anything. (Either when it burst or before this.) The car has never been in an accident, either.We'd used the car to get home from work in, and the heat had been on, but it was definitely not hot in the car. We were chilly, even with our jackets on. The temperature outside was in the low to mid twenties.The bursting happened about twenty minutes after we got home.My daughter said that she heard a boom, and then the window broke. (The backyard is right next to the driveway.) My neighbor, who came outside when he heard her yell and got there before I did, said that she was still in the yard when he came outside--and really, even if she weren't, she's six--there's no way that she could break my car window. Again, from everything that I could see, the window literally exploded, bursting outward. There were no objects in or near the car that could have hurt the window (a few pieces of junk mail and a kindergarten art project were in the front seat), so no chunks of ice sliding off the roof or anything. How could this happen? The best I can come up with is some mumbled mumbo-jumbo about air pressure and heat, but...well, but surely that's not it, because if it were, car windows would burst all winter long. Further, what do I do now? Is there any chance that I could get the dealership to cover it, since as far as I can tell, this was some sort of defect in the window itself? I have a thousand dollars deductible on my insurance, and I figure that replacing a window will certainly be less than that--it's not even worth calling them, right? (Plus I fear that this would be seen as an "act of god", meaning that they wouldn't cover it anyhow.) I have a tarp over the window (closed into the door) in the meantime--is there anything else I should do to protect the interior of the car?

• Answer:

  If you Google for 'exploding car window' or 'car window exploded' you find a lot of similar reports, even blog posts and Flickr sets, from drivers of a variety of vehicles. It appears at least at first glance that a lot of people did get it covered by insurance. I would personally let the dealer know because if it was a flaw caused during manufacturing, others could be affected by it as well. There are a bunch of reasons people give for why the glass could have spontaneously "exploded," such as a defect in the glass, uneven stresses on the window from the frame, a defect in a rear defogger and/or a defogger inadvertently left on. I don't know much about this so I can't vouch for the accuracy, but I found an interesting summary left by user Oberon in http://ths.gardenweb.com/forums/load/cars/msg031653252210.html.