[HN Gopher] Doorbell camera catches rare footage of meteorite st...
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Doorbell camera catches rare footage of meteorite striking home's
front walkway
Author : hodgesrm
Score : 100 points
Date : 2025-01-25 14:45 UTC (8 hours ago)
(HTM) web link (www.cnn.com)
(TXT) w3m dump (www.cnn.com)
| andrewfromx wrote:
| that's insane! What is the speed its going?
| lucb1e wrote:
| TL;DR some 200 km/h
|
| The article says some 20 km/s, but that's its speed in space.
| The video is crap (just repeats the same footage four times, no
| slow motion) but downloading that m3u8 with yt-dlp and running
| it frame by frame in mpv: it shows up on one frame (well, two
| because it does interlacing) and then there's already a dust
| plume. The camera looks pretty high up, maybe 3 meters? With it
| first appearing roughly in front of the camera (vertically),
| that would mean a lower bound of 3 meters in 1/30th of a
| second, or 1/15th if this interlacing makes it 15fps in reality
| which I suspect, meaning somewhere north of 324 or 162 km/h in
| either scenario
|
| It looks like a decent-sized stone to me on that one frame,
| maybe the size of one's hand? Call it a 15cm sphere for
| simplicity, WolframAlpha says that has a 177 cm2 cross-section
| and https://www.omnicalculator.com/construction/stone comes up
| with a few kilograms (4-8) depending on the type of rock, with
| which we can fill in a terminal velocity calculator
| https://www.omnicalculator.com/physics/terminal-velocity to get
| an estimate of 320 to 450 km/h depending on its weight
| (probably towards the higher end given that it's metallic) --
| assuming we got the size anywhere near correct, of course
|
| Edit: someone posted
| (https://news.ycombinator.com/item?id=42822256) a YouTube link
| where it's visible for 2 frames! (I'll call them frame 1, 2,
| and plume.) Now the prize question is how far up it was in the
| first frame and what angle it comes in at. The biggest chunk
| looks to be about the same size in both frames, at least to
| within video compression artifacts, so that doesn't help figure
| out the angle. It also travels nearly twice the distance in
| pixels between frame 2 and plume as compared to frames 1 and 2,
| which would be an angle thing or a video compression thing. I
| don't see an interlacing effect in frame 2 anymore, and frame 1
| is duplicated (the youtube video runs at 24 fps). I think this
| has passed through too many compression / re-encoding layers to
| say anything useful sadly. For the heck of it: say that it was
| 5 meters up in frame 1 and it takes 2/24ths of a second to
| traverse that, that would be 216 km/h
|
| Loading the audio tracks into Audacity, the YouTube version
| shows nothing until ~180ms before impact if I'm being generous,
| whereas the CNN version contains inaudibly faint noise starting
| around ~350ms before (don't know that that's attributable to
| the meteorite, but at least there's data instead of a flat
| line), which I guess tells us that CNN's version has undergone
| fewer recompressions. Sadly, I don't think there's enough
| samples to measure the doppler effect, also given that it's not
| going directly towards/away from us (the shift is more like
| 60deg probably?). Three meters are traversed in 24ms at
| 450km/h, and while there's audible noise on both YT and CNN for
| ~85ms before impact, the spectra are just too noisy for me to
| make it out. Someone more experienced with measuring dopplers
| could have a stab at it, though
|
| More editing: it is only now that I properly read the article
| (I know, shame on me, I guess DIY is more fun) and it says a
| "professor of Earth and atmospheric sciences at the University
| of Alberta" also tried this approach but hasn't figured it out
| yet: '"We are working on analyzing the video to see if we can
| say more about the meteorite's fall -- including speed," Herd
| said.'
|
| I'm curious if we can figure this out by dropping rocks at
| different speeds until we get a plume that expands as fast as
| this one (since we have enough footage to reliably see that)
| and leaves a similar-sized mark
|
| Final edit, another source someone posted
| (https://news.ycombinator.com/item?id=42822765) includes: "He
| said the rock that struck at Velaidum's home was probably
| travelling at least 200 km/h by the time it made impact." The
| news report video in that source also includes a picture of the
| pavement after cleaning up the dust, showing marks of some 3cm
| on the ruler included in the shot. Doing the same terminal
| velocity calculator as mentioned earlier, a dense type of stone
| of 3cm would be slowed to 196 km/h by our atmosphere
| NotYourLawyer wrote:
| If we know its rough size, should be easy to figure out its
| terminal velocity. It's just a rock.
| pizzafeelsright wrote:
| That would definitely do damage to somebody's skull.
|
| Airspeed, drag, and terminal velocity and all that I would assume
| it's going subsonic and appears to be quite brittle.
|
| The angle also appears to be consistent with what I've seen other
| impacts produce in the 40 degrees.
|
| The lack of sonic boom and camera catching it I am curious if
| this happens on the daily with nominal observation.
| mr_toad wrote:
| Terminal velocity of meteorites is around 200-400 mph. If it
| hit you in the skull it could be lethal.
|
| https://space.stackexchange.com/questions/12774/what-impact-...
| ajross wrote:
| I love that on HN you need to cite StackOverflow to document
| that dropping a rock on someone's head hurts a lot.
| oidar wrote:
| I figured there would be a hand full of instances of people dying
| from meteorites falls, but they have only ever bruised a person:
| https://www.smithsonianmag.com/smart-news/only-person-ever-h...
| Retric wrote:
| "only well-documented case of somebody being hit by a
| meteorite"
|
| Significantly more people were alive in prehistory than in
| recorded history. So it's likely one or more of them were
| significantly injured.
| qoez wrote:
| Is that actually true? Population growth has exploded in
| recorded history even though pre-history has years to its
| advantage
| pavel_lishin wrote:
| Five seconds' worth of googling shows that an estimate of
| Hominid population before 200,000 years ago is anywhere
| between 2 billion to 20 billion.
|
| https://en.wikipedia.org/wiki/Prehistoric_demography#Homini
| d...
|
| This is one of those things that's probably incredibly
| difficult to estimate with any level of accuracy.
| layer8 wrote:
| Why stop at hominids?
| pavel_lishin wrote:
| Because of the context of the discussion we were having.
| layer8 wrote:
| People don't normally consider all hominids as "people".
| And if you do, you might also add dolphins, corvids, and
| the like.
| saalweachter wrote:
| When I put all the population estimates into a spreadsheet
| the last time it came up, the number of person-years lived
| can be roughly divided into thirds, one third from the dawn
| of anatomically modern humans to the beginning of
| agriculture, one third from the beginning of agriculture to
| 1600, and the remaining third from 1600 to today. By
| current estimates, well acquire an equal slice of lived
| experience between now and 2100.
| renewiltord wrote:
| Well, the important thing is the number of person-hours not
| the number of people since meteorite death has to be pretty
| random.
|
| If 5 people took turns existing in sequence that's not more
| likely for a human observation than one human over that time.
| It only matters how many hours where humans were available to
| die and that's roughly matched between prehistory and the
| last 100 years.
| Retric wrote:
| If you want to get a really good estimate it's worth
| considering the odds that either 0 or thousands of people
| dying in the same event when people are living in dense
| cities etc.
|
| Tunguska over London would have had a serious death toll
| where an airburst in a remote area didn't. But you're going
| to see deaths in an area with a population density of 1 per
| square km or 100,000/km2.
| comboy wrote:
| It's not even clear that total amount of people who lived in
| prehistory is higher than amount of people currently alive
| today.
|
| https://en.wikipedia.org/wiki/World_population
| dinkblam wrote:
| Your own source contradicts you: "The total number of
| humans who have ever lived is estimated to be approximately
| 100 billion. "
| shalmanese wrote:
| Pre-history is defined as the time before writing was
| invented or ~5000BC. The number of people alive before
| then is significantly smaller than 100B.
| Retric wrote:
| Written records of events didn't start everywhere as soon
| as the first group invented writing.
|
| More relevant when considering the criteria of well
| documented evidence, a hypothetical ship on an ocean
| voyage in 1500 is likely to just disappear. Let alone a
| random West African goat herder in 2200BCE.
| layer8 wrote:
| The Wikipedia page links to this [0] article as a source,
| where the table states an estimated 9 billion "ever lived"
| at the 8000 BCE mark, and 55 billion at the 1 CE mark. The
| end of prehistory isn't too well defined, but it's usually
| taken to be around 5000 BCE (if not later). So while it's
| not very precise of course, from those estimates it
| certainly looks like more humans lived in prehistory than
| now, by a few billion at least.
|
| Given that the world population is predicted to peak at
| about 10.5 billion roughly 60 years from now, it also looks
| like this won't change anytime soon.
|
| [0] https://www.prb.org/articles/how-many-people-have-ever-
| lived...
| Retric wrote:
| That's on the low end of estimates.
|
| For comparison there's still 300,000 Wild West African
| Gorilla today and they're extremely restricted in range,
| share that range with modern humans, etc.
|
| Human populations in prehistory were believed to average
| somewhere in the 1-15 million range which puts 10B at the
| very low end estimate with 100+ billion being considered
| plausible. There was at least one major bottleneck but
| humans predate the last ice age.
|
| PS: Calling anything history before we have any surviving
| text to work with is also a stretch.
| marcosdumay wrote:
| There's probably a Tunguska-sized event at some point that
| claims 99.99% of all meteorite victims and wasn't registered
| because everybody that knew about it died in it.
| pavel_lishin wrote:
| According to some witnesses, the Tunguska event itself
| killed three people:
| https://en.wikipedia.org/wiki/Tunguska_event
|
| I wonder if any people died as an indirect result - someone
| startled by the flash of light or the bang, who stepped
| into the path of a carriage, or just slipped and fell and
| cracked their skull.
| somat wrote:
| There is one theory that that the biblical story about the
| annihilation of the city of Sodom was brought about by a
| large air-burst meteor, think Chelyabinsk and add a couple
| of order of magnitude.
|
| https://pmc.ncbi.nlm.nih.gov/articles/PMC8452666/
|
| However, note that when I was trying to find the original
| paper, that is, something more substantial than the popular
| news blurbs that are everywhere, I found wikipedia was less
| than impressed with the evidence.
|
| https://en.wikipedia.org/wiki/Tell_el-Hammam
|
| Anyhow, I suspect a lot of our long term generational
| history gets turned into religion and legend, that is to
| say, the legendary events probably happened but like a good
| fish story the facts get shifted over the years.
| layer8 wrote:
| According to the estimates in
| https://www.prb.org/articles/how-many-people-have-ever-
| lived..., (substantially) less than 55 billion lived in
| prehistory, and more than that lived since (the current
| estimated number of humans ever having lived being above 117
| billion).
| fortran77 wrote:
| Well, actually it caught a meteor striking, leaving behind a
| meteorite.
| shireboy wrote:
| You are technically correct. Which is the best kind of correct.
| alentred wrote:
| Ooooh, thank you! For a few years now I thought I was the
| only one ever citing that source of the infinite wisdom.
|
| Having said that, the meteor was probably from the planet
| Urectum.
| wileydragonfly wrote:
| All I ever caught on my cameras was someone coked out of their
| mind crashing into my backyard and carefully making an escape at
| 3am.
| not_a_bot_4sho wrote:
| I want this to be a joke. But I'm not willing to bet money on
| it.
| pavel_lishin wrote:
| I've caught a variety of suburban wildlife, including one
| enterprising hominid who decided to help himself to my bicycle.
| whamlastxmas wrote:
| YouTube link: https://youtu.be/c0gnYzhTL5A?si=3fS6uvL3_5LtE7La
| lucb1e wrote:
| Thanks! This shows it for 2 frames instead of 1 because there
| is no channel overlay showing the location (Canada) on top of
| the meteorite
|
| Link without tracking for the lazy btw:
| https://youtu.be/c0gnYzhTL5A
| smitelli wrote:
| Pro Tip: While the YouTube player is paused, the comma and
| period keys move back/forward by one frame. (Memory aid, < and
| > but without using Shift -- assuming US PC keyboard layout.)
| filchermcurr wrote:
| Here's the video without any news overlay:
| https://drive.google.com/drive/u/0/folders/1YfVmkgXgwGVcxdqW...
| lifeisstillgood wrote:
| This has made my day - just a tiny reminder we live on a ball Of
| rock plummeting through space - awesome !
| tialaramex wrote:
| A damp rock.
|
| It looks pretty though, which we wouldn't have known a century
| ago - a small, pretty, damp rock. It's not much, but it's all
| we'll ever have.
| wink wrote:
| I would have thought the stone tile would have shattered.
| ajross wrote:
| No, it was tiny. Very likely it had decelerated to terminal
| velocity and was just falling like (literally) a rock.
| xattt wrote:
| The guy who owns the house is a theologian scholar (1). Message
| from above, perhaps?
|
| Original CBC article is here (2).
|
| (1) https://islandscholar.ca/people/jvelaidum
|
| (2) https://www.cbc.ca/news/canada/prince-edward-island/pei-
| char...
| I_dream_of_Gen1 wrote:
| like, really old news...
| j-bos wrote:
| Why is CNN DRM locking a video that doesn't belong to them?
| foxglacier wrote:
| They probably licensed it from the owner so it protects him.
| HelloUsername wrote:
| Several times posted this week:
|
| https://news.ycombinator.com/item?id=42694277
|
| https://news.ycombinator.com/item?id=42719167
|
| https://news.ycombinator.com/item?id=42699537
|
| https://news.ycombinator.com/item?id=42733580
|
| https://news.ycombinator.com/item?id=42742065
|
| https://news.ycombinator.com/item?id=42721622
|
| https://news.ycombinator.com/item?id=42807205
|
| https://news.ycombinator.com/item?id=42750821
|
| https://news.ycombinator.com/item?id=42780394
|
| https://news.ycombinator.com/item?id=42745712
|
| https://news.ycombinator.com/item?id=42736932
|
| https://news.ycombinator.com/item?id=42767349
| belter wrote:
| This link is the new '42'
| adzm wrote:
| Despite chronically checking HN this is still the first I've
| seen of it!
| dboreham wrote:
| TikTok is your friend.
|
| Oh wait...
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(page generated 2025-01-25 23:02 UTC)