Tonight at some point before 8:00 PM Eastern Time, the world will experience what is known as a "leap second". There will be a minute of time that is 61 seconds long. Today, June 30, will be approximately one second longer than usual, and official atomic timekeeping will factor in this second before turning over to July 1. This strange concept has a fascinating history and explanation; however, it is also a cause of concern for market traders around the world, who fear that this extra second will disrupt global operations.