Sight is very effective at giving exact information over considerable distances. If the viewed object is moving, it can tell us much about the speed and direction of this movement as well as allowing us to identify it. For all this to happen we need to see it. This means our eyes have to be looking in the correct direction. Light waves do not go around objects very well, so we cannot see an object if it is hidden behind another object. This does put limits on what sight can achieve. Sight is an easy sense to use, because during the day we are surrounded by light supplied by the sun. This light bounces off things and brings us information about them. However, when the sun sets on a cloudy night, the light is mostly gone, and then vision shall become less useful as a sense.