There are many cameras on Earth (professional and amateur) pointing at our Solar System, watching its inhabitants for clues and events that might help us understand our planet's past – and possibly our future. Still, it's particularly joyous when one of those cameras catches something entirely unplanned because it happens to be pointing in the right direction, at the right time, to serendipitously see something rare and exciting.
This is what happened this week when multiple cameras on Earth caught something very large smash into Jupiter on September 13. Amateur photographers around the world caught the bright flash of what appeared to be an impact in Jupiter's upper atmosphere. Incredibly, if confirmed, this will be only the eighth impact event observed on Jupiter since comet Shoemaker-Levy 9 collided with the gas giant in 1994 and made history, providing the first-ever direct observation of two bodies colliding in the Solar System.
As the largest planet in the Solar System, Jupiter's gravitational influence means it is also the most impacted, we just rarely see these collisions.
Thankfully, amateur astronomers have their telescopes and cameras pointing to the sky, catching most of the events recorded so far, including an asteroid or comet hitting the gas giant in 2016 and an asteroid collision in 2019.
In fact, it was the 2019 impact that allowed astronomers to calculate just how often Jupiter is hit by something large enough to create a flash visible from Earth. It's thought around 20-60 objects smash into the planet each year, so this new one being the eighth ever recorded shows how rarely we actually catch these events.
Of course, half of these collisions happen on the far side of the gas giant and are fleeting, lasting mere seconds as the space rocks disappear into Jupiter's atmospheric layers, burning up in a fiery death and producing the telltale flash of light. If we miss the flash, other impact phenomena such as cloud disruption are often masked by the winds and swirling cloud layers around the massive planet.
However, it would appear our rate of detecting them is increasing. From the first seen comet collision in 1994, the next observed was in 2009, and since then they have been documented in 2010, 2012, 2016, 2017, 2019, 2020, and now 2021.
Due to its massive gravitational pull, Jupiter may act as a shield for Earth, sucking up any stray space rocks that may be heading our way, although there's also a good chance it also helps sling the occasional asteroid or comet towards us too. This time, however, it appears it took one for the team, so thanks, Jupiter!