What are the sparks?

A reader asks, Dear AutoRacing1: I have a question about IRL cars and the showers of sparks that the cars emit when under load in turns or, eerily, when crashing. I do not recall ever seeing open wheeled race cars behave this way on any level of motorsport or under any other sanctioning body including SCCA, Champ Car, FIA, etc. Are the showers of sparks engineered by teams and/or specified by IRL officials for dramatic value? Thank you Mark Lee, Cincinnati, OH

Dear Mark, The sparks come from the skid blocks under the car rubbing the track. The teams run the cars as close to the ground as possible for maximum speed, and although Indy is very smooth, the slightest ripple causes the car to bottom out because they are already so close to the ground. Mark C.