An image showing a large scar on the surface of planet Jupiter has members of NASA scratching their heads.
   
Scientists are not certain what hit the giant planet, but some think the large gash may have been caused by a collision with a comet almost the size of planet Earth.

NASA released images that show the impact occurred near the south pole and caused debris to fly into the upper atmosphere.
    
Amateur astronomer Anthony Wesley, 44, from Australia is being credited for the discovery.

"We owe a huge debt to him for picking up on these things," said planetary scientist Leigh Fletcher at NASA's Jet Propulsion Laboratory.
    
Wesley said he was about to give up his stargazing for the night on a backyard 14.5-inch reflecting telescope but then he noticed the spot on Jupiter and alerted NASA.

"I thought (it) likely to be just a normal dark polar storm," Wesley told Reuters from his home at Murrumbateman, north of Canberra."However as it rotated further into view and the conditions improved I suddenly realized that it wasn't just dark, it was black in all channels, meaning it was truly a black spot."

Fifteen years ago, pieces of the comet Shoemaker-Levy 9 crashed into Jupiter as well.