Jupiter is becoming quite popular planet...for impacts, that is. On August 20 at 18:22 UTC, two amateur astronomers in Japan independently recorded an apparent impact on Jupiter. The first report came from Masayuki Tachikawa of Kumamoto city.
Masayuki Tachikawa of Kumamoto city was first to report the event. Soon after Tachikawa made his report, Tokyo amateur astronomer Aoki Kazuo discovered that he also had recorded the fireball.
The above image was recorded by amateur astronomer Masayuki Tachikawa from Kyushu. The image was recorded using a webcam attached to a six-inch f/7.3 refractor telescope. This version of the image, with the added arrow graphic, was posted by Japan television station KYODO.
The separation between the two observing locations, approximately 800 km, rules out the possibility that the event took place near Earth and reinforces the association of the fireball with Jupiter. The most likely explanation for the event is that a small comet or asteroid hit the gas giant.
The August 20 impact was the third time in only 13 months that amateurs detected impacts on Jupiter. The earlier events occurred on July 19, 2009 and June 3, 2010. The July 19 impact is now thought to be caused by an asteroid about 500 meters (1,600 feet) wide. The resulting impact in the cloud layer was approximately the size of the Pacific Ocean. The June 3 impact was reported by Australian amateur Anthony Wesley, who was at the time watching live video feed from his telescope. Wesley's observation was confirmed by amateur Christ Go, who was taking video from his telescope in the Philippines. Unlike the July 2009 event, the impact from June 3 of this year left no visible scar or debris in the clouds, causing astronomers to be uncertain as to the actual depth of the impact penetration.
In 1994, Comet Shoemaker-Levy 9 broke into more than 20 pieces and pelted Jupiter with a string of impacts. At the time, astronomers estimated that cometary impacts could occur on Jupiter every 50 to 250 years.
Because Jupiter is receiving impacts more frequently, researchers are rethinking their estimates of Jupiter impact rates. In addition, many researchers are calling for a global network to monitor Jupiter around the clock in order to measure the Jupiter impact rate.