 By far the most massive planet in the Solar System , Jupiter can capture objects relatively frequently , but the size of SL9 makes it a rarity : one post @-@ impact study estimated that comets 0 @.@ 3 km in diameter impact the planet once in approximately 500 years and those 1 @.@ 6 km ( 0 @.@ 99 mi ) in diameter do so just once in every 6 @,@ 000 years . 
