This month, we got a rare view of an apparent asteroid ramming into the planet Jupiter. It struck so hard the explosion was visible all the way back here, some 400 million miles away. In the video below you have to look carefully at the right-hand side of the planet, because the impact is faint. But it is there. That faint blip is the force of a celestial object exploding with the power of a nuclear bomb.
This video was captured by an amateur astronomer with a telescope in Austria. It's proof that with just relatively simple equipment, anyone can witness the awesome power of the cosmos and physics in their own backyard.
The impact was also confirmed by a second amateur's observation in Ireland, as captured in this video below.
(Both videos via Phil Plait's Bad Astronomy blog on Slate.)
Was it really an asteroid? NASA thinks so.
"Yes, it looks very much to us like the impact of a tiny asteroid on Jupiter," Paul Chodas, who studies asteroids and manages NASA's Center for Near-Earth Object Studies, tells me.
Chodas says he found out about the collision "like you did" — that is, by logging on to the internet. He says NASA scientists will be able to study these grainy YouTube videos and make estimations about the size of the asteroid and the force of its impact.
Chodas notes that observers haven't seen any scars on the face of the planet, as had occurred with bigger collisions. That makes him suspect that the asteroid was small, perhaps on the scale of the one that exploded over Chelyabinsk, Russia, in 2013 — about a couple dozen meters across.
Witnessing impacts on Jupiter helps astronomers determine the number of these small asteroids in the solar system. "We're not able to see asteroids down to this size range; they're simply too faint," he says. "This is a different way for us to be able to get some indication of their population."
Knowing the population size of these small asteroids then lets scientists extrapolate Earth's risk for colliding with one. This single impact won't change those models, he says, but it does confirm what they've already predicted.
That prediction is that Jupiter will get hit by an asteroid every other year or so. But don't worry: Jupiter gets hit more often than Earth does because of its size and proximity to a greater number of asteroids. The asteroids also hit the planet with a much greater velocity and release much greater amounts of energy.
Here on Earth, we get small collisions only once every 50 years or so.
"The asteroid that burned up over Chelyabinsk, Russia, in 2013 was 19 meters across, and it exploded with the energy of 500,000 tons of TNT," Plait explains. "Now multiply that by 25, and you can see how it doesn’t take all that big a rock to hit Jupiter for us to be able to see it from Earth."
NASA doesn't monitor Jupiter continuously, and welcomes the contributions of citizen scientists. "Really I think the amateurs are playing a key role in allowing us to understand the frequency of these impacts on Jupiter," Chodas said.