ESA: Small meteorite will safely impact atmosphere tonight over northern France
twitter.com
twitter.com
Edit: I was expecting that it would be too far away, also with Aachen's city glow and the highway, that nothing would be visible, or at best, a point appearing and disappearing at basically the same location in the haze of city glow. Compared to that, I'm absolutely blown away. Will post a video in a few minutes, just took the 380MB thing off my phone, now cropping to the right ~10 seconds, rotating, that stuff
Edit again: here we are finally https://lgms.nl/files/Sar2667-Aachen.mp4 Quite sad it defocused, and you'll need an x264 decoder in your browser I think (I used `ffmpeg -c:v copy` to avoid losses, so it's whatever encoding my phone uses), should work in a local video player if you download it.
A friend found this one https://www.youtube.com/watch?v=8owpwqzBEPA
Location estimate, based on where I saw it plus this video https://twitter.com/meteordoc/status/1624967987294765059 from Brighton looking over a pier: <https://www.openstreetmap.org/?mlat=50.0761&mlon=0.5335#map=...>. It became visible to me at 03:59:13 GMT+1/CET and exploded 5 seconds later, with my phone's clock sync being ~0.6s behind so it might have been 03:59:14
Got so lucky finding that Brighton video as the 2nd result earlier. Spent another 15 minutes looking for a third angle but the "looking east", "looking south" indicated angles are either implausible or too inaccurate to be useful. A Paris video is of such quality that I couldn't for the life of me find out which buildings are in view to map it to an angle. This location guess is going to be my final estimate.
How did you check your phone's time synchronization?
Per this thread https://twitter.com/tw__astro/status/1624908400902504451 it seems my time is a bit off, though. I took the filename and just checked the time offset in the video. Was considering checking metadata but thought 'nah, those few milliseconds difference'. However, exiftool says 2023:02:13 02:59:29, file name is 20230213_035256.mp4. Adding those three seconds to my previous guess comes out to the tweet's time.
As I write this, I'm still... what's the word, excited? Thrilled? Like, I'm still not down to baseline relaxed. It's really just five seconds of light show, but looking at an astronomical event unfolding, knowing this is hundreds of kilometers away in northwestern France, the tiny voice in the back of your head as you see it explode "could they have been wrong about it being just 1 meter?" I wasn't truly scared at any point but the combination of feelings and awe is still a little bit with me.
Desert Fireball Network (Curtin University)
http://fireballsinthesky.com.au/
One way amateurs can help is by setting up a meteor detection system and engaging in a little citizen science. A few years ago this was an expensive task, but now with a Raspberry Pi and some simple electronic parts it’s much easier.
It just isn’t important to most people. It’s understandable - our gods used to be in the sky - now they are on the television.
I've been watching meteor showers for about 40 years, but the 2016 Peseids was just amazing. At it's peak, we were getting 2 or 3 large meteors per minute. We couldn't stop saying "wow" about one before another would streak 1/3 across the sky. And I'm sure that we saw over a dozen bolides, at least one or two bright enough to cast shadows on the ground. It was that spectacular. I don't remember when the moon set but I believe that it was gone by the time the show peaked between 1 and 2 am. Truly a night I'll never forget.
A perfect occasion to... laachen?
TIL that refers specifically to feelings that would cause laughing. Took me a while to get your pun, also because (to this dutchman) aachen is two sounds removed from lachen and not one like it might be for a german (where they hardly differentiate between short a and long aa).
I find it hard to describe feelings (in any language), maybe "shocking" is a better word than exhilarating? But that sounds more negative than I mean it. The german word that comes to mind (I hardly speak german so this might be far off) is aufregend which dict.cc says translates to both shocking and thrilling, maybe that's a better description because it's not specifically about being happy or scared but rather a neutral energetic feeling? "Getting worked up" might be a translation of aufregen but it doesn't sound like what an english speaker would say in this situation due to connotation.
Look at it from the bright side. You will never forget to manually focus the next time a meteorite passes by. :)
- I wouldn't know what shutter time and ISO setting to use, or if it should need to be adjusted during the event when I want to be watching it
- I was already fairly late to the party to start thinking about and configuring this stuff: I didn't know of the +/-1 second window at the time, only saw the 10-minute window (which was a good thing because an adjacent tweet in that thread said it wouldn't be visible even halfway here so I might not have gone out at all!)
- The phone will try to use a broader light range ('HDR') in default mode, which is not something I understand (my confusion about that is a comment in itself), but not in pro mode. It doesn't work for extremes like capturing the sun as part of any picture, but in most cases it will work as though you took two pictures with slightly different shutter times and it'll scale values and stitch the pictures so that the dark areas are not pitch black and the bright areas are not full white. That seems like something I'd not want to disable, as it might make it capture more detail of the bright parts of the event.
... but as I write this, I realize that I can select 'auto' for shutter, ISO, white balance, etc. also in pro mode. Configuring the shutter is the main reason I use pro mode for, so it hadn't occurred to me that there is also a little 'auto' button for that in the corner! Not at the time, and not at the beginning of this comment either ^^'. I can set focus to infinity and only lose "HDR", not automatic selection of other settings. That might actually be worth it, don't know. But that's a good thing to be aware of, so thanks for making me realize this :D
NP :)
So cool to see how far our detection of these objects is coming along, especially for something as small as this was.
> Got so lucky finding that Brighton video as the 2nd result earlier. Spent another 15 minutes looking for a third angle but the "looking east", "looking south" indicated angles are either implausible or too inaccurate to be useful. A Paris video is of such quality that I couldn't for the life of me find out which buildings are in view to map it to an angle.
There is a building visible in your video, so with that info I could figure out the angle to get a third line. I currently have these two: https://snipboard.io/rBNozt.jpg
Or if someone simply knows where to find someone who has a calibrated observation with range finder, I'd also be happy to find the location that way :D somehow I'm having a lot of trouble finding any information about this stone.
It surprised me how many different combinations of meteor-moon constellations I saw in the various videos being posted. For some, the moon was very close; for me, the moon was like 110° removed I think (somewhere over my left shoulder). Maybe, knowing it was in England, it could help me to narrow down the scenarios (perhaps from an area down to a line?), but I don't have the experience to do that in a time-effective manner and I don't know if it would significantly help with the outcome.
The moon at that time had a diameter in the sky of 0.5225 degrees (it doesn't change much), so you can also get a reasonably accurate idea of the zoom level of the video, taking the size of the moon in pixels when it is most in-focus (and accounting a bit for glare).
Does this help at all? The line on the left is when the object first becomes visible in the video, and the line on the right is when it explodes and disappears from view - it's actually pretty similar to what you had already.
What puzzles me is that the other end is so far off that it's outside what I had previously screenshotted of the map (so not visible when intersecting the two). From my POV, the angle difference between start and end was close to zero, like it came fairly straight down. That would be in line with yours if it roughly came towards me, as it roughly indeed did afaict, but I don't think the Brighton pier video had that wide a range. (I should re-watch it to be sure, though.)
There are also various reported angles on this event page https://ams.imo.net/members/imo_view/event/2023/937 but half of those honestly look in line with what I previously noticed where a video might have a description "facing east from Jersey" which would mean Paris is in the ~center of their view, not the English channel in front of Dieppe, resulting (because no visible landmarks) in lines like these horizontal/vertical ones <https://snipboard.io/d3rkNI.jpg>. Compared to all that, your report is definitely more useful! It would seem the meteor traveled at least 30 if not 50 km in those ~five seconds!
<https://twitter.com/esaoperations/status/1624901825785724929>
Looks as if the predicted entry point will be over Rouen.
That tweet cites Richard Moissl (also on Twitter):
<https://twitter.com/Richard_M_F/status/1624890692156751872>
(For those reading this: I'd of course emailed hn@ycombinator.com, largely with the text in my comment. It's an effective way to get attention / make changes to posts.)
That's about three hours from now as I write this.
My very off-the-cuff estimate is that a 1m impactor might mass anything from a few hundred kilos to a few tonnes, depending on composition (less for ice / chondrites, more for a heavy nickel-iron meteorite).
Looking forward to the skycam views.
- The centroid of probability is near Rouen.
- Earlier/later impact probability would be along a path along the movement/orbit of the impactor. I'm going to guess that that's largely east-west track, though with a possible orbital inclination.
- The probability distribution across that range is likely far higher near the centre than at the extremes.
- Relative motion of Earth's rotation (~1,600 km/hr at the equator, less than that at the latitude of Rouen) is a much smaller component than the likely relative velocity of the meteorite (~20 km/s).
- 20 km/s +/- 10 minutes ... gives 12,000 km as a possible range around the impact site.
There's also the question of accurately noting the original position of the impactor.
That said: good question and I'd love to hear from someone who knows what they're talking about.
Thought also comes to mind of Aristotle's future contingents, "there will be a sea battle tomorrow" ...
I think the issue with your reasoning is that when you are dealing with orbits, you cannot really talk separately about position and (relative) velocity. Instead, for a given orbital trajectory, the position completely defines the speed. Moreover, your estimate might tell us how far _in space_ the impact would be given +/- 10min, but since both earth and asteroid are moving though space that doesn't really tell us much about how far apart it would be in an earthbound reference frame.
In practice, I don't think they can accurately measure the position OR speed of an object like this... Instead, they make multiple observations over time and can fit the "shape" of the orbit, which can be done even with a fair amount of noise since we know all orbits are elliptical. If the object's orbit doesn't intersect Earth's, there's no impact. If the orbits do interest, there _may or may not_ be an impact event. To determine this, you have to figure out if both the object and the earth will be at that intersection point, _at the same time_.
I'm guessing this is why the quoted uncertainty is given in minutes.
Mind that the geometry of the collision might truncate that considerably. Again, I'm not claiming expertise here, and the "straight maths" rubric isn't a justification for correctness so much as explaining how I arrived at the number.
To successfully apply DA in this problem, we should start by noting that since we are talking about impact, it is a foregone conclusion that the earth and the asteroid will be in the same place at the same time (your application instead was related to figuring out where earth and asteroid would be in relation to each over at a given time).
Once you've specified that they will be at the same place, asking where it lands _on earth_ amounts to asking which part of the earth will be facing the asteroid at that time. Since there is a quoted uncertainty of +- 10min, the range of outcomes is almost entirely defined by the angular distance that the earth with travel in those 20min -- about half a time zone!
This gets us much closer to the actual projection from ESA. The actual central location at the nominal time is defined almost entirely by the direction the asteroid is approaching from -- i.e. the relative inclination and phase anomaly of the orbits. So, the rest of the projected range can be chalked up to uncertainty on the geometric fit of the object's orbit based on astrometric observations. Which we can't apply DA to without further information.
Let's take a moment to remember this beautiful story: https://www.smithsonianmag.com/smart-news/reagan-and-gorbach...
Apparently, predicting arrival for natural near-earth objects is rare enough we're still in single digits. \
Very cool!
At their speeds they're impacting the atmosphere in a similar way a bullet impacts water (it disintegrates and loses speed rapidly, causing a big splash).
https://www.youtube.com/watch?v=c9ch5mtxmLk
Also, here's a great recording of the shock wave, illustrating your point:
F15s could fire anti satelite missiles in early 1980s. Who knows what "toys" are available 40 years later.
The benefit of this sort of task is in both cases the target object doesn't move of its own accord, so presumably if you can predict the path of the object with enough precision then it would work. Clearly we can pinpoint a 1m satellite, but no idea on the error bars for a 1m meteoroid.
A small nuke could definitely obliterate a 1-meter rock, if you don't mind contaminating a large part of Europe with radioactive dust.
[0] https://en.m.wikipedia.org/wiki/Category:Nuclear_anti-aircra...
Not sure if they arent much bigger than an anti sat missile though.
Assuming charitably that the missile could generate an intercept, you would probably get some sparks, maybe more or less depending on how much of the rock is actually nickel and iron. But basically, the rock is a rock. An AIR-2 Genie likely wouldn't bother it all that much beyond maybe a surface glazing and some neutron activation. The most a Sidewinder will do is expensively nothing.
If they can bust few (double digit?) meters of concrete, they could bust a rock. Assuming they dont miss and assuming they dont slip.
https://en.m.wikipedia.org/wiki/Bunker_buster
Obviously it would have to be some combination of an anti sat missile (so it can fly in space) and a bunker buster (so it can crush throigh rock).
I'm not sure that counts as shooting it down. In the context of a celestial object usually "shoot it down" means "deflect it so it misses earth".
In general, it also is extra difficult to calculate the exact last little bit of a trajectory that will impact earth because the force models start getting really wild as something gets very close to earth - approximations stop working.
What kind of forces? I assume you're talking about the space part, before atmosphere, so I would assume it's the same gravity effects that you also get in space, just that gravity is a bit larger value. I wrote a gravity simulator at lgms.nl/p/badgravity so I have a bit of an idea but am definitely no expert (the thing doesn't do any sort of collisions and assumes 2d point masses), so I'm curious what you mean. Especially with the earth dominating the gravity and not needing to use N-body physics anymore, it should get more accurate if anything.
Could you elaborate or do you have a link? Or do you simply mean the compounding effect of having used N-body approximations for the interplanetary space part of the trajectory leading to different starting points for the final approach?
> This is just the seventh time an #asteroidimpact has ever been predicted before it happens - a sign of the rapid advancements in global asteroid detection capabilities!
Usage notes Meteor (streak of light in night sky): Not to be confused with meteoroid and meteorite (cause and remains of a meteor), or asteroid and comet (celestial bodies).
This post is mistitled. The original Tweet is:
A 1-meter meteoroid (small #asteroid) has been detected and is expected to safely strike Earth's atmosphere over northern France between 3:50-4:03 CET.