 The visible scars from the impacts could be seen on Jupiter for many months . They were extremely prominent , and observers described them as even more easily visible than the Great Red Spot . A search of historical observations revealed that the spots were probably the most prominent transient features ever seen on the planet , and that although the Great Red Spot is notable for its striking color , no spots of the size and darkness of those caused by the SL9 impacts have ever been recorded before . 
