 Comet Shoemaker – Levy 9 was the ninth periodic comet ( a comet whose orbital period is 200 years or less ) discovered by the Shoemakers and Levy , hence its name . It was their eleventh comet discovery overall including their discovery of two non @-@ periodic comets , which use a different nomenclature . The discovery was announced in IAU Circular 5725 on March 27 , 1993 . 
