On the night of March 17, two amateur astronomers, one in Austria and one in Ireland, had their telescopes trained on Jupiter and captured an unexpected event: a comet or asteroid met its explosive demise when it hit the large planet's atmosphere.
Jupiter tends to get hit by a lot of objects, including the famous Shoemaker-Levy 9 comet that pelted big brother Jove in 1994. “Jupiter watchers have since seen a big impact site in 2009 subsequently imaged by Hubble, two bright-flash events in 2010, another bright-flash event in 2012, and now this bright-flash event in 2016,” Heidi Hammel a researcher at the Space Science Institute tells Miriam Kramer at Mashable.
According to Phil Plait at Slate’s Bad Astronomy Blog, Jupiter only gets hit by something observable from Earth about once every year. So it was extremely lucky that the amateur astronomers caught the event on tape. The first to realize his fortune was Gerrit Kernbauer in Mödling, Austria. He posted the video to YouTube and the online astronomy community took notice.
A Facebook post with the footage caught the attention of John McKeon, an amateur astronomer in Swords, Ireland, who decided to review the footage of Jupiter he’d recorded the same night. “I was surprised to learn I had this data,” McKeon tells Kramer. “Within minutes I had gone through a few of my video captures from March 17 and there it was!”
The image almost didn’t come to light. Kernbauer writes in the description of his YouTube video that he hesitated to look through his video footage since the viewing conditions that night were not ideal. “Nevertheless, 10 days later I looked through the videos and I found this strange light spot that appeared for less than one second on the edge of the planetary disc,” he writes. “Thinking back to Shoemaker-Levy 9, my only explanation for this is an asteroid or comet that enters Jupiter’s high atmosphere and burned up/explode[d] very fast.”
Phil Plait writes that he thinks the object was probably not giant, just tens of meters wide. But because of Jupiter’s massive gravity, it draws objects to it at five times the velocity they approach Earth. That means even small objects hit with massive energy, creating a flash that can be seen several planets away.
But the explosion wouldn’t have been recorded at all if not for the expansion of cheap, high-quality telescopes, cameras, and video equipment that allow amateurs to make significant contributions to astronomy.
“Professional astronomers have only limited time on large telescopes, which means that they can take exquisitely detailed observations but can’t spend long staring at one target in the sky; time on major telescopes is simply too valuable,” Emily Lakdawalla, senior editor at the Planetary Society tells Kramer at Mashable. “Amateur astronomers make fundamental contributions to astronomy research, and this recent observation of an impact on Jupiter is a perfect example of why.”