Jupiter, the gas giant that may have obliterated most of our solar system's original set of planets, got a taste of its own medicine a couple of weeks back: Slate's Phil Plait reports that a small comet or asteroid appears to have collided with the planet March 17.
Serendipitously, the impact was captured on film by Austrian amateur astronomer Gerrit Kernbauer, who observed the event with a 20 cm telescope. And, um, super serendipitously, it was also caught on camera by John McKeon, an amateur stargazer using a 28 cm telescope near Dublin.
"I was surprised to learn I had this data," McKeon told Mashable. McKeon's video was sent to Plait after he called for more recordings of the event on Twitter. "I only realized it after a Facebook update on March 28 about an observer in Austria (Gerrit Kernbauer) seeing an impact on Jupiter," McKeon said.
Plait explains in his post that the object — which remains unidentified, but was likely either a meteor (metal-y rock) or a comet (rock-y ice) — may have hit Jupiter with incredible force, because of how strong the massive planet's gravitational pull is and how physics works:
Given how brief the flash was, and how bright, I’m sure it wasn’t terribly big, probably in the tens-of-meters wide range. I know that sounds small, but remember, Jupiter has ferocious gravity, and velocity is critical here! The energy released by an object slamming into another depends linearly on the mass (double the mass, double the energy), but on the square of the velocity: double the velocity, quadruple the energy.
The average velocity of an object impacting Jupiter will be five times greater than an object colliding with Earth, meaning that the impact energy will easily be 25 times as high — which is why even a rock smaller than a football field can make a splash visible to amateur telescopes from over 400 million miles away. In fact, similar flashes on Jupiter have been caused by rocks just 10 meters (32 feet) across.
It's likely that Jupiter has impacts like these pretty frequently. Some scientists even think that the planet protects Earth from devastating collisions by flinging space debris out of the solar system with its powerful gravitational pull. But you could also argue that Jupiter's incredible gravity, which kept rocks around it from forming into new planets, is responsible for the very existence of the asteroid belt. And it's possible that the very same gravity that keeps some space rocks out of our path actually sends others right into our back yard.
In any case, scientists definitely want to know more about how often Jupiter has run-ins with asteroids and comets. And amateur stellar sleuths can help out in a big way.