Chelyabinsk + 10: The anniversary of the day the sky exploded over Russia

This article was originally published in the Bad Astronomy Newsletter by Phil Plait, an astronomer and science communicator, as well as a friend of Asteroid Day.
He writes his Bad Astronomy Newsletter three times a week at badastronomy.substack.com.

Ten years ago last week, on Thursday, February 14, 2013, I was sitting in my office at home wrapping up my day. It was around 10:00 p.m. or so, and I had been doing some more reading about the asteroid 2012 DA14 — a roughly 30-meter space rock that was going to pass by Earth the next day at the hair-raising distance of only 28,000 kilometers.

Much of the news coverage was pretty good (including, modestly, my own) but fearmongers were out in full force with sketchy YouTube videos and the other usual tauroid feces, so I was poking around looking at debunking it.

So you can imagine my frame of mind when, just as I was about to sign off the internet for the evening, I got a note from someone saying, hey, have you seen this? And it was a link to a YouTube video.

Clicking it wearily, I watched shaky camera footage showing a twilit sky. Suddenly, a brilliant blob appeared on one side, gaining brightness rapidly as it streaked across the sky and leaving a huge vapor trail behind it. Checking the video notes, it said it was from a city called Chelyabinsk, in Russia.

Pbbbbt, I remember thinking. I had just seen a handful of faked videos of exactly this kind of event, some of them cleverly done to fool people into thinking they were real. And with so much baloney being spread at that time about DA14, I was more than usually skeptical of this video.

Then I got a second note from a reader linking to a different video. This showed the same event but from a different angle. Like the first one it looked like it could maybe kinda sorta be real, but again my skepticism overruled that thought: One of the faked videos I had just watched showed a “meteor” coming in as seen from two different angles, applying parallax to the CGI to give it a whiff of sincerity. So again, I was unconvinced.

Then a third came. And a fourth. Um.

Still not convinced, but debating with myself about the authenticity, another video went up showing the view of a huge vapor trail, far larger than any airplane contrail, outside a building in the Russian morning. I was just about to marvel about how real that looked when suddenly the video erupted with an immense BOOM and the camera went wild, the sound of shattering and falling glass and people yelling.

[Note: This is the same footage I remember watching, though not the original account. I searched but couldn’t find it on YT anymore.]

Oh. Um. Yeah, that seems like a detail a bit too picky for someone to hoax. It was pretty much at that point I walked to my office door and yelled up to my wife, “Hey Cel, yeah, a big meteor just exploded over Russia and I think I’m going to be up for a while longer!”

I spent the next several hours hastily trying to gather as much info as I could from videos and social media, then news reports, and finally some official sources. Carefully noting how the event was unrelated but shockingly coincidental with DA14, I wrote up an article for Slate magazine, which had just hired me as a freelancer three months before. It ran the next day, and wound up generating more traffic than I probably ever got on anything else I wrote during my tenure there.

As for the event itself, it was the largest Earth impact since Tunguska in 1908. We learned a lot about it over the next few weeks, months, and years. The Chelyabinsk asteroid was 19 meters in diameter, stony, and was moving about 19 kilometers per second relative to Earth when it entered our atmosphere.

I’d tell you more, but hey, as it turns out there’s a whole Scientific American article I wrote about the event that you can read! I’d like to publicly acknowledge and thank my editors there, especially Dan Vergano, for getting it ready and published in time for the actual anniversary; I pitched the idea only a week before when I realized the tenth anniversary was coming up.

… and also for updating the article at the last minute when the small 1-meter rock called 2023 CX1 was discovered and hit our planet only two days before!

I found out about CX1 (initially called Sar2667 before being given an official name) on Twitter on the evening of February 12, 2023, not long after it was first discovered by astronomer Krisztián Sárneczky at the Hungarian Piszkéstető Observatory (Sárneczky is credited with discovering or co-discovering nearly 400 small objects, including the asteroid 2022 EB5, which also impacted Earth!).

Incredibly, it only took minutes before confirmation observations were made, and the asteroid trajectory determined to intersect Earth over the English Channel. Hundreds of observations were made in just a few hours, and the impact time narrowed down to an accuracy of one second. With several hours lead-time, a lot of people were ready to watch it, and within minutes of its impact Twitter lit up with incredible videos and photos.

I think this is my favorite:

You can see the sudden glow of the meteor, the trail of luminous vaporized rock left behind, and then several rapid flashes as the rock disintegrated due to the huge pressure of ramming through our atmosphere, each smaller piece suddenly flaring brightly as they too burned and fell apart, then the final flash as all the smaller bits burned up at the same time. It was very much like Chelyabinsk in miniature.

Even with such short notice there were enough observations of it to get an excellent trajectory, which allowed people to go look for meteorites that may have hit the ground. And that was successful too!

Amazing. And very important scientifically! Having an actual meteorite from the asteroid to study combined with the footage of its entry will give planetary scientists a lot of info on how such rocks behave in space and as they ram through our air at hypersonic speeds. And that means incrementally better understanding of what we can do to prevent larger ones from hitting us.

Also? Meteorites are awesome. I have a chunk of Chelyabinsk that was given to me by Richard Drumm.

2023 CX1 was only the seventh asteroid seen before it impacted (another last-minute update I had to make in my SciAm article since I had mentioned only six had been seen before impact). That number will go up a lot in the coming years, and I expect the rate to accelerate as we get better at finding these small rocks. As it happens Chelyabinsk came from the direction of the Sun so it would’ve been unlikely to be seen before impact even now, despite having been much larger than CX1. We need more eyes on the sky!

I talk a bit about that in the SciAm article too (as well as what we can do if some incoming asteroid or comet has us in its crosshairs), and I just found out a few days ago about a new ESA space mission being planned called NEOMIR that will be able to detect much smaller rocks — even Chelyabinsk-sized! — because it uses infrared light to detect them, which is more efficient than looking for them in visible light. It will also look in a direction more or less toward the Sun, where it’s impossible to search from the ground. Nice. It’s planned for launch around 2030.

Until then, we can learn the lessons of past impacts: Those objects are out there, and if we do nothing, then an impact is inevitable. The good news is, we’re doing a lot.