While we Earthlings were fretting about the California recall, the Universe had other stuff to do. 

On Monday, September 13, at about 6:39 P.M. Eastern, Harald Paleske of Germany and José Luis Pereira of Brazil both caught on video a pretty significant object impacting the surface of Jupiter.  From the size of the impact, a rough guess is an asteroid or comet a few hundred feet wide.  That’s no slouch; a hit by something that size on Earth would leave a crater about a mile wide.

A still frame from Paleske captures this nicely:


Paleske doesn’t seem to have posted his video yet, but Pereira has.  Here too you can see Io’s shadow and the impact at about the same latitude.  Zoinks!

Jupiter was being watched at this time because its moon Io was passing in front of the planet, and this makes for fun observing and good photos.  Looking at our chart of Jupiter’s Galilean (Big Four) moons, we see that on the afternoon of Sept. 13, Io is indeed making that pass:


Thanks for tipping us off, Io!

Of course this event is nothing like Comet Shoemaker-Levy 9, which broke into at least 24 pieces, all of which slammed into Jupiter over six days in July, 1994, sending plumes almost 2,000 miles high and leaving obvious scars on the face of the planet that lasted for months until they were dispersed by Jupiter’s high-altitude winds:

Scars left on the face of Jupiter by comet Shoemaker-Levy 9

The impact of Shoemaker-Levy 9 was equivalent to at least a thousand times the Earth’s entire nuclear arsenal; that is, a surefire civilization annihilator if it had hit Earth.  At the time it was thought that impacts like this in the modern Solar System are quite rare, but in fact since 1994, this latest impact is the 8th known — significant enough to be observed, that is — on Jupiter. 

When did the last one happen?  At least that we know about?  Why, that was way back in 2019, caught by Ethan Chappel in Texas:

An impact on Jupiter caught by Ethan Chappel on August 6, 2019 while looking out for the Perseid meteor shower.  This is a montage of photos, but still looks like a bit of a turbulent atmosphere for this one

That impact didn’t have noticeable scarring afterwards, but we’ll see in the coming days if any scarring is spotted this time.

What does this impact frequency mean for Earth?  Well, let’s do a dumb calculation, with lots of questionable assumptions!  Jupiter’s surface area is about 120 times that of Earth’s, and Jupiter has had 9 hits big enough to be observable in 27 years, or once every 3 years.  (And we’ve probably missed a couple, too.)  If the same density of rogue stuff is flying around Jupiter and Earth, then we ought to have one of these mile-wide-crater-inducing impacts once every 360 years.  If we missed any Jupiter collisions, that number would come down some.  The last ballbuster collision with Earth was in 1908 (the Tunguska Event), so that estimate is probably not too far off.

The year is 1908, and it’s just after seven in the morning. A man is sitting on the front porch of a trading post at Vanavara in Siberia.  Little does he know, in a few moments, he will be hurled from his chair and the heat will be so intense he will feel as though his shirt is on fire.

That’s how the Tunguska event felt 40 miles from ground zero.

But, wait!  An actual astronomer agrees with my silly calculation:

[Don] Yeomans and his colleagues at JPL’s Near-Earth Object Office are tasked with plotting the orbits of present-day comets and asteroids that cross Earth’s path, and could be potentially hazardous to our planet.  Yeomans estimates that, on average, a Tunguska-sized asteroid will enter Earth’s atmosphere once every 300 years.

Hey, I could work at JPL!  (Painting the walls, maybe….)

But for now, we have a couple of very happy amateur astronomers.  Pereira said“For me it was a moment of great emotion as I have been looking for a record of this event for many years.”  As you can see on the comments section of his YouTube submission, he has gotten a boatload of Parabéns!

Pereira with the 275-mm f/5.3 Newtonian reflector he used to make the discovery from São Caetano do Sul, Brazil


Keep on looking up, amateur astronomers.  You’re doing a bang-up job!

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This is a Creative Commons article. The original version of this article appeared here.


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