While driving at around 45mpg i heard a very loud sound like a gunshot or a huge rock hitting my truck. when it was safe i pulled over to check for any damages. none where observed. the next day i heard wind noise and no windows open. i started to open the sunroof and heard glass breaking. i got home and looked on roof and saw a huge hole in panoramic portion of sunroof and 1000's of pieces of glass being held up by liner. no vandalism or accident caused this. if anyone in backseat they could have suffered considerable cuts.