On August 7, Ethan Chappel was the only human to witness a planetary impact. He caught a small asteroid hitting Jupiter and producing a bright flash of light. Researchers have been able to use his observations to work out the size and type of meteorite and even how often these objects smash into the gas giant.
Chappel was conducting video observations when he caught the flash, and used open-source software called DeTeCt to analyze his footage. DeTeCt was designed by fellow amateur astronomer Marc Delcroix and Ricardo Hueso from the University of Basque Country to study such impacts.
The data were analyzed by the duo as well as independently by Ramanakumar Sankar and Csaba Palotai of the Florida Institute of Technology. The data point to a stony-iron meteorite 12-16 meters (39-52 feet) across weighing 450 tons. The meteorite disintegrated about 80 kilometers (50 miles) above Jupiter's clouds and released energy equivalent to 200–250 kilotons of TNT. That’s roughly half of the yield of the Chelyabinsk meteor or about 15 times the energy released by the Hiroshima nuclear bomb.
“This is the first impact flash at Jupiter found using the DeTeCt software," Delcroix said in a statement. "These detections are extremely rare because the impact flashes are faint, short and can be easily missed while observing the planets for hours. However, once a flash is found in a video recording it can be analysed to quantify the energy required to make it visible at a distance of 700 million kilometres.”
The project has been running for years and Delcroix and Hueso have now presented some results at the European Planetary Science Congress & Division for Planetary Sciences of the American Astronomical Society Joint Meeting 2019 in Geneva. They were able to give a better picture of impacts in the Jupiter and Saturn systems.
“With six impact flashes observed in 10 years since the first flash was discovered in 2010, scientists are becoming more confident in their estimates of the impact rate of these objects in Jupiter," said Hueso. "Most of these objects hit Jupiter without being spotted by observers on Earth. However, we now estimate 20-60 similar objects impact with Jupiter each year. Because of Jupiter’s large size and gravitational field this impact rate is 10,000 times larger than the impact rate of similar objects on Earth.”
The two hope that more and more astronomers will employ DeTeCt so that the analysis can be refined.