[HN Gopher] Small asteroid to hit Earth's atmosphere today
___________________________________________________________________
Small asteroid to hit Earth's atmosphere today
Author : dgacmu
Score : 168 points
Date : 2024-09-04 13:03 UTC (9 hours ago)
(HTM) web link (earthsky.org)
(TXT) w3m dump (earthsky.org)
| koliber wrote:
| It was discovered 8 hours ago!
|
| I have mixed feelings about this. One the one hand, I'm super
| excited that we can go from discovery to wide dissemination
| within a few hours. On the other hand, what's the chance of
| something like this happening with a much bigger asteroid.
| rogerrogerr wrote:
| We'd at least see them earlier, because much bigger asteroids
| are much bigger.
| ben_w wrote:
| > On the other hand, what's the chance of something like this
| happening with a much bigger asteroid.
|
| Lower.
|
| As size increases there are fewer bigger asteroids to begin
| with, and they are also easier to spot.
| davidcuddeback wrote:
| > _On the other hand, what 's the chance of something like this
| happening with a much bigger asteroid._
|
| Bigger asteroids are easier to see.
| ithkuil wrote:
| that's right.
|
| another metric that affects the ... impact ... of such an
| event is also the speed of the asteroid. Unlike size, I
| suspect higher speeds would make it harder to spot (and once
| spotted there would be less time to take action)
| BurningFrog wrote:
| Asteroids are just as visible at any speed.
|
| Though warning times _will_ be shorter the higher the
| relative speed is.
| bumby wrote:
| I think the OPs point was:
|
| If we are only surveying a portion of the sky at a time
| and a faster asteroid spends less time traversing that
| portion, the likelihood of detection is lower.
| AnimalMuppet wrote:
| Faster asteroids leave longer streaks.
| krisoft wrote:
| I'm not sure if you are joking.
|
| Assuming you are not. What kind of "streak" you are
| thinking about? Are you thinking about comets with their
| tails? Or motion blur?
|
| Because if motion blur I would expect an asteroid on a
| collision course to have none. (at least in the short
| timeframe before the collision) Because "Constant
| bearing, decreasing range" is how a collision looks like
| from a first person perspective.
| AnimalMuppet wrote:
| Your last paragraph is correct, but only very close to
| the collision. Things in orbit around the sun don't move
| in straight lines, even if their paths are going to
| intersect. The earlier you see it, the less it's moving
| straight at you.
|
| (Of course, if it's going to hit you, the faster it's
| going, the more straight at you its path is at the same
| distance. But for the same amount of "not straight at
| you", faster leaves a bigger streak.)
| ithkuil wrote:
| Yeah given that were talking about objects that are
| colliding with the earth, the faster they will come
| closer to us the less time we'll have to spot them
| morning-coffee wrote:
| > On the other hand, what's the chance of something like this
| happening with a much bigger asteroid.
|
| The same as it's always been, which is to say you can live your
| life without worrying about it.
|
| If our technology advances such that we can observe/find more
| and more of these, that doesn't affect the chances that a
| particularly sized asteroid hits the earth or not.
| sandworm101 wrote:
| >> such that we can observe/find more and more of these, that
| doesn't affect the chances that a particularly sized asteroid
| hits the earth or not.
|
| Maybe under classical rules, but we know know that the act of
| observation collapses the range of possible outcomes,
| potentially locking us into a collision by an asteroid that
| previously existed only as a probability cloud.
| dmd wrote:
| That's not how any of this works.
| ivanjermakov wrote:
| As far as we know, quantum effects do not apply to big
| space rocks
| whimsicalism wrote:
| ?? quantum effects apply to everything, but for large
| objects the expectation is classical
| krisoft wrote:
| Curious use of the double questions marks when the
| following sentence reveals that seemingly you did
| understand the point the commenter was making.
| whimsicalism wrote:
| because the claim "quantum effects do not apply to large
| objects" is not the same as "large objects behave
| classically in expectation". the former claim is flat
| false
| toss1 wrote:
| Ya, if your "asteroid" is a subatomic particle in the
| quantum regime, maybe. But the impact of one such particle,
| even ultra-high-energy cosmic rays, can be safely ignored.
|
| Everything of asteroid size, or on the Torino Scale [0] is
| in the realm described by classical mechanical physics, and
| it will merrily follow it's existing trajectory whether or
| not we know about it in advance.
|
| So, the only question is whether or not it's better to know
| it's arriving some hours/days/weeks in advance.
|
| * Certainly better in cases like this (observable but
| harmless).
|
| * Definitely would be better in cases like the Chelyabinsk
| meteor [1] which caused a fair amount of damage and some
| injuries, if people would be given a warning to avoid being
| near windows, etc.
|
| * Absolutely better in cases of regional devastation to
| global catastrophe where we have time and resources to
| alter the trajectory to reduce or eliminate harm. Even just
| enough lead time to only move many of the people out of the
| impact damage region is a definite benefit.
|
| * YMMV in cases of in cases of regional devastation to
| global catastrophe where we lack time and resources to
| alter the trajectory or move people. Is it better to know
| you'll die in X hours or be surprised?
|
| So, I'd say everything below Torino-5 is definitely a good
| discovery (I think this is a Torino-0], and everything
| above depends on circumstances. Overall, a very good idea.
|
| [0] https://en.wikipedia.org/wiki/Torino_scale
|
| [1] https://en.wikipedia.org/wiki/Chelyabinsk_meteor
| whimsicalism wrote:
| it wouldn't make it more likely and the chance of an
| asteroid deviating from classical trajectory even by a
| centimeter is less likely than any event ever observed
| before
| m4rtink wrote:
| Bigger object should reflect more light, making detection more
| likely.
|
| In very simplified terms, say its roughly spherical, the amount
| of light grows with the second exponent, so twice bigger object
| reflect 4 times as much light - but it is also potentially 8
| times as heavy (eq. volume grows with third exponent) & thus
| more dangerous.
|
| Trade-offs. :)
| krisoft wrote:
| > Bigger object should reflect more light, making detection
| more likely.
|
| That assumes that the detection is photon constrained and not
| "nobody is looking in most directions" constrained.
|
| It doesn't matter even if the asteroid is carrying a lit
| magnesium torch if nobody is looking for it systematically.
|
| I'm not saying that it is the case. In fact I'm asking: are
| we photon constrained or are we constrained by the rate we
| are scanning the sky?
| svachalek wrote:
| Both, but in practice the coverage of dangerous sized
| objects is pretty good already and when the Vera Rubin
| Observatory goes online it will get an order of magnitude
| better.
| leke wrote:
| Yep, it could be that one day you go to work and your town gets
| destroyed before you manage to get home and hug your family
| goodbye.
| exitb wrote:
| According to NASA [1], asteroid needs to be larger than 25
| meters to cause localized damage. It'd need to be larger than
| 1-2km to cause globally observable consequences.
|
| [1] https://www.nasa.gov/solar-system/asteroids/asteroid-
| fast-fa...
| pdonis wrote:
| _> what 's the chance of something like this happening with a
| much bigger asteroid._
|
| Negligible. As I noted upthread, objects large enough to be do
| significant damage if they hit Earth and are on trajectories
| that could bring them close to Earth are routinely spotted
| years in advance.
| tommoor wrote:
| > This is only the ninth time that humankind has discovered an
| asteroid before it impacts Earth
|
| TIL. It seems like it's basically luck if someone is looking
| through a telescope in the right place at the right time?
| ziddoap wrote:
| Luck has a lot to do with it, sure, but we're (thankfully) a
| bit more advanced than just hoping someone is looking through a
| telescope at the right place/time.
|
| NASA's Center for Near Earth Object Studies does a lot of neat
| work related to this. For example, Sentry [1], the NEOWISE
| mission [2], etc.
|
| [1] https://cneos.jpl.nasa.gov/sentry/
|
| [2] https://www.jpl.nasa.gov/missions/neowise
| yourapostasy wrote:
| Thank you for your useful comment. It sent me down a brief
| rabbit hole of looking for a grid of amateur telescope owners
| cooperating for NEO object detection. I found eSTAR for the
| big boy telescopes [1] [2], but nothing for enthusiasts. I
| ran across NEO Surveyor that launches in September 2027, will
| run for 5 years, and is aiming for 90% coverage [3], so I
| suppose a grid of amateurs contributing telescope time into a
| software-driven grid and detection system won't be helpful?
|
| [1] https://indico.cern.ch/event/423169/contributions/1890157
| /at...
|
| [2] https://ui.adsabs.harvard.edu/abs/2002SPIE.4845...13S/abs
| tra...
|
| [3] https://www.jpl.nasa.gov/missions/near-earth-object-
| surveyor
| schiffern wrote:
| You might be interested in the work of Robert Holmes.
|
| https://www.techbriefs.com/component/content/article/33153-
| q...
|
| https://en.wikipedia.org/wiki/Robert_Holmes_(astronomer)
|
| https://www.youtube.com/watch?v=MWLDvuK_4qU
| sapiogram wrote:
| Although there's always luck involved, it was discovered by the
| Catalina Sky Survey, a survey specifically designed to spot
| near-earth objects.
|
| Their main telescope has a very large field of view (20 square
| degrees), and takes only 30 seconds per exposure, giving it
| many chances to get "lucky".
| ck2 wrote:
| Does anyone know how the 10,000 Starlink satellites and the
| other 30,000 LEO competitors by the end of the decade are
| going to affect spotting near-earth objects?
|
| I would have a hard time believing "not at all".
|
| Vaguely related this is my favorite amateur astronomer
| spotting accident ever, capturing supernova an hour before it
| happened which hasn't been done before:
|
| https://www.popsci.com/amateur-astronomer-photographs-
| birth-...
|
| makes me wonder when the sky becomes so difficult to see
| through if we are going to lose all that enthusiastic effort
| goodcanadian wrote:
| There are a number of projects dedicated to looking for near
| earth objects that could impact the earth. Pan-Starrs and Atlas
| are the ones that come immediately to mind for me, but there
| are others.
| moffkalast wrote:
| Well yes, but these are only spotted so late because they're so
| small, which also makes them harmless. Anything that would be
| large enough to do damage would be also easier to detect
| sooner.
| pdonis wrote:
| Not really. What the article fails to tell you is that there
| have been many, many, many _more_ than nine times that
| asteroids have been spotted, often years in advance, where the
| initial data had wide enough error bars to make an Earth impact
| possible, but continued observation quickly ruled that out and
| predicted, correctly, that the asteroid would pass near the
| Earth but miss it. True, those asteroids were quite a bit
| larger than 1 meter wide, but as the article 's description of
| the "impact" shows, a 1 meter wide asteroid isn't a real threat
| anyway.
| dmurray wrote:
| In sailing and shipping, another vessel is set for a collision
| course for you if and only if its direction from you doesn't
| change (assuming both keep constant speed).
|
| Is this roughly the same for orbiting bodies? If so, it would
| seem that things on a collision course would be harder to
| detect, as they're indistinguishable from bodies far away that
| don't move. Possibly orbital mechanics change this
| significantly, but over the course of a few days the earth's
| trajectory is pretty much straight.
| dghughes wrote:
| And it seems to have just barely made it in the asteroid class
| being >1m if less it would be a meteoroid.
| cscheid wrote:
| Yes, up until recently. The Vera Rubin observatory will change
| that quite a bit, and soon. Most observatories and telescopes
| are currently aimed at deep field (very long exposures of tiny
| portions of the sky). There are a few surveys meant for
| transients (supernovae, variables etc) and those are also well
| suited for near earth objects: look at the Catalina sky survey
| and the zwicky transient facility. When I was (very mildly)
| involved, the Vera Rubin observatory expected its first 25% of
| the mission to be overtaken by observing new near earth
| objects, even as its mission was to catalog variable stars and
| spot supernovae and other transients.
|
| Some interesting stories about how these surveys work today and
| how they will work in ~10 years. Right now, it's so rare to
| spot a weird thing in the sky that the alarms are all verified
| by grad students in graveyard shifts. When the new
| observatories come online, there won't be enough grad students
| in the world :) so it'll all be ML.
| simmonmt wrote:
| Thank you for heads up will get my code submitted before world
| ends.
| firtoz wrote:
| You need to send the backups towards space, with a trajectory
| to come back towards Earth when we have restarted civilisation
| zeeZ wrote:
| Ah, so it was _that_ kind of monolith!
| swayvil wrote:
| You can hear meteors. They hiss as they go by a hundred miles
| overhead. Which is weird of course. There are theories.
| Electromagnetic effects and such.
| schiffern wrote:
| *a hundred kilometers
|
| More info:
|
| https://earthsky.org/space/whoosh-can-you-hear-meteors-strea...
|
| https://www.space.com/35908-meteor-sounds-mystery-solved.htm...
|
| https://www.youtube.com/watch?v=JqXZbrDZrVU
| swayvil wrote:
| "mystery solved". Ho ho. These people gobble a nice story
| like mommy's pancakes.
| hcarvalhoalves wrote:
| Last time I witnessed a meteor shower (I guess it was early
| 2000s or late 90s in Brazil), I swear I could hear it, but it
| was so faint that wasn't sure if I was imagining the sound.
|
| BTW, I was watching the meteors from the attic, where my dad
| had a music studio, so lots of transducers around. The radio
| waves theory from the article would make sense.
| darkest_ruby wrote:
| As f Philippines is a tiny town and everyone can go out and just
| watch. Specify exact location!!
| MentallyRetired wrote:
| The article contains a map with where they think it will scrape
| the atmosphere
| goodcanadian wrote:
| The fireball will likely be visible from 100s of kms away.
| nelblu wrote:
| There's quite a bit of cloud cover and rain, I hope they can see
| it. https://www.windy.com/17.613/121.733?clouds,14.807,123.827,6
| yawboakye wrote:
| we have come so far. i vaguely remember a similar-ish
| discovery/announcement was made in the early 2000s. well, i was
| too young and too stupid to check the news myself (there was no
| internet, just tv and newspapers anyways) but i quite remember
| that respectable town leaders searched for answers in their
| bibles and qur'ans. strange times they were.
| adrianmonk wrote:
| Why does the graphic have two streaks and a triangle? I can't
| figure out where to get more information.
|
| In case it's not clear what I mean, one streak is greenish and
| the other is yellow/red. The triangle is black and one edge of it
| is colored red and seems to connect the centers of the streaks.
|
| I'll take an educated guess:
|
| (1) they are two different elevations
|
| (2) they are essentially heatmaps of strike probability elongated
| because of the earth's rotation
|
| (3) the triangle is a right triangle situated in a plane
| perpendicular to the earth's surface so that the red line
| indicates the angle.
|
| It's funny that they'd have a strike location on the surface
| given that they said it won't hit the surface. But maybe it's a
| standard way to do the graphic, in which case it represents where
| it would strike if it were big enough even though it's not.
| layer8 wrote:
| It's clearer in the image here:
| https://x.com/esa/status/1831307613205615044
| tecleandor wrote:
| I think it's the uncertainty areas. One it's 100km height and
| the other for 0m. It can be seen better on these links [0] [1].
| I think it's done this way to show the trajectory.
| 0: https://x.com/esa/status/1831307613205615044 1:
| https://x.com/esa/status/1831337534950924348
| JW_00000 wrote:
| > [T]he coloured regions represent impact probabilities (to 1,
| 3, and 5 sigma). The red-orange-yellow area shows where the
| asteroid would reach Earth's surface if there were no
| atmosphere in the way. > > But there is an atmosphere! So we
| also mark in green where the asteroid will be when it is at an
| altitude of 100 km. This is roughly where it will begin to
| break up and therefore where observers could start seeing a
| fireball. > > The red line would be the asteroid's trajectory
| between those two points, if it were still one solid object,
| which it won't be.
|
| from https://x.com/esaoperations/status/1831349538583445693
| 0xbadcafebee wrote:
| This is a little depressing, but I just realized if we ever have
| interplanetary war, we'll just push big space rocks into their
| orbit.
| cut3 wrote:
| Future earth wars will have bombardments from space, no need to
| wait until we are on other planets.
| simmonmt wrote:
| May I suggest
| https://en.wikipedia.org/wiki/The_Expanse_(novel_series)
| tway_GdBRwW wrote:
| Heinlien, The Moon is a Harsh Mistress, 1966
|
| https://en.wikipedia.org/wiki/The_Moon_Is_a_Harsh_Mistress
|
| The moon colony uses this to win its freedom.
|
| However, The Expanse is also a great book
| vhodges wrote:
| Related: Footfall and Lucifers Hammer (Both by Niven and
| Pournelle)
| sgt wrote:
| Hopefully better than the TV show. Man, that was a terrible
| ending.
| troyvit wrote:
| It is better, and yeah for anybody who read the series the
| ending was especially awful. It's been awhile but I feel
| like they packed at least one book into the last 2-3
| episodes of the last season. The book series still has a
| weird 30 year jump, but you stay there awhile at least.
|
| For the first few seasons of the show I thought they did a
| good job, even though (or maybe because?) the show departs
| from the books in a lot of ways. But they tried to cram way
| too much into the last season and just made it seem like
| jibberish.
| oaththrowaway wrote:
| Kind of part of the plot to "The Moon Is a Harsh Mistress"
| shepherdjerred wrote:
| You might like planetary annihilation
|
| https://planetaryannihilation.com/
| FredPret wrote:
| This is a plot point in the Bobiverse books.
|
| The delta-v required for a heavy asteroid may make it more
| practical to send a fleet of nukes though.
| jjk166 wrote:
| If you have the technology to push big space rocks onto a
| collision course, you have the technology to push big space
| rocks off a collision course.
| explorigin wrote:
| As long as you can see them in time.
| stoperaticless wrote:
| Interception is a different process and usually it is more
| difficult.
|
| Example of it being different process: bullets are
| accelerated by gun powder, but stopped by various armor.
|
| Example of increased dificulty: interception rockets have
| higher demands on speed and agility. (If somebody tries to
| evade, you have to be faster)
| duckmysick wrote:
| "The war after the next world war will be fought with sticks
| and stones" gains a new meaning. What would the sticks be
| though? Thor rods?
| aziaziazi wrote:
| > The object is harmless
|
| [impact streak cover some human infrastructures]
|
| I get the odds of landing in someone roof are tiny in this rural
| area -probably smaller than meeting a grizzly in NYC- however I
| won't call a grizzly "harmless". Perhaps the panic induced by
| _not_ calling it harmless would cause more harm.
|
| https://maps.app.goo.gl/1LE4EnzBz13gH3zt5
| dgacmu wrote:
| I believe - IANAA - that it will entirely burn up in the
| atmosphere:
|
| https://www.nasa.gov/solar-system/asteroids/asteroid-fast-fa...
| https://physics.stackexchange.com/questions/47754/minimum-si...
|
| > Space rocks smaller than about 25 meters (about 82 feet) will
| most likely burn up as they enter the Earth's atmosphere and
| cause little or no damage.
|
| (This one is 1m, so it's a pretty good margin.)
| vhcr wrote:
| The latest tweet confirms it will fall in the ocean.
|
| https://x.com/esa/status/1831337534950924348
| supermatt wrote:
| Relevant infographic on asteroid threat (from the article):
| https://www.esa.int/ESA_Multimedia/Images/2018/06/Asteroid_d...
| JW_00000 wrote:
| It'll break up and partially burn up, partially turn into
| smaller meteorites, before hitting the surface of the Earth.
| IanKerr wrote:
| It's always very impressive to me seeing our ability to detect
| such obscure objects in advance getting better and better. We'll
| soon have such good detection capabilities that we may start to
| take these kinds of predictions for granted the same way we take
| accurate weather forecasts for granted. Can't wait to see the
| local meteorologist talking about actual meteors.
| wantsanagent wrote:
| Astrophysics peeps, why is it that the danger seems to be only
| tied to the mass of the object. Given p=mv is (relative) speed
| essentially the same for all of them or otherwise
| inconsequential?
| NotEvil wrote:
| Not a astrophysicist but I would guess it's due to atmospheric
| drag. Higher velocity objects will burn more quickly
| anal_reactor wrote:
| Not into astrophysics, but I guess "faster asteroids experience
| higher forces when going through the atmosphere, therefore
| burning faster". Another explanation could be "most of
| asteroid's speed comes from Earth's gravity, not from it's
| initial state".
|
| These are just random guesses though, so I could be completely
| wrong.
| ddahlen wrote:
| The range of mass is typically much larger than the range of
| velocities. There is an upper bound to the speed for the vast
| majority of things which are dangerous (escape velocity of the
| solar system). However there are orders of magnitude
| differences in mass.
|
| Velocity is important though.
| seabass-labrax wrote:
| Adding a little context for those not familiar with orbital
| mechanics: the speed of a circular orbit is directly related
| to its distance from the barycenter (i.e. the Sun). The
| asteroid belt is between the orbits of Mars (orbiting at
| 24km/s) and Jupiter (13km/s). Whilst an asteroid that strays
| far enough to hit Earth (orbiting at 30km/s) is by definition
| not in an exactly circular orbit, nor one always between Mars
| and Jupiter, the difference in speeds isn't that great. That
| accounts for ddahlen's point about the limited range of
| velocities.
|
| A very rough calculation of mine involving a hypothetical
| asteroid in a elliptical orbit extending as far as Jupiter
| and right down to Earth, assuming no difference in orbital
| inclination to Earth and no significant gravitational
| perturbations, would result in a relative speed of 5km/s. The
| actual impact speed would be greater due to Earth's own
| gravity, adding an extra 11km/s.
|
| Not all asteroids are from the asteroid belt, but I am under
| the impression that visitors from the outer solar system
| (which could be as fast as the upper bound that ddahlen
| mentions) are much more infrequent than stray asteroid belt
| objects, so the median impact speed would still be relatively
| slow.
| wantsanagent wrote:
| Ahh escape velocity hadn't thought of that, thanks. So it
| would take something like Oumuamua to be much faster?
| ddahlen wrote:
| We have spotted a grand total of 2 interstellar objects,
| they were moving faster, but are many orders of magnitude
| less numerous then the local stuff.
|
| Just doing some back of the envelope calculations, looks
| like Omuamua was moving about 165,000km/hr (relative to
| Earth) when it was about at Earths orbital distance.
|
| This speed is not actually a crazy number, it is a lot
| faster than the majority of things which could hit us, but
| there are geometries of things in our solar system which
| can reach these relative velocities. (For example things in
| retrograde, IE: reverse orbits) can lead to basically
| escape velocity + earths velocity.
| isk517 wrote:
| Not astrophysicist but here's a article from the Lunar and
| Planetary institute about impact speeds from astrological
| objects https://www.lpi.usra.edu/exploration/training/illustrat
| ions/....
|
| Looks like there is not a significant amount of variance in
| asteroid speed so mass would be the biggest deciding factor.
| calfuris wrote:
| I'm not an astrophysicist, but I was part of a D&D group with
| one a few years ago and the topic came up (outside the game).
| In practice the speeds fall into two fairly tight clusters
| (asteroids and comets), but you don't even need that to justify
| focusing on mass. There's a hard lower bound on everything, and
| also a hard upper bound on any object that is part of our solar
| system, and it works out to at most a factor of 40ish in
| kinetic energy between the slowest and fastest possible
| impacts. The masses of objects of interest have a much wider
| range.
| rznicolet wrote:
| Everything coming in speeds up when it falls to earth.
|
| Tiny stuff burns up completely in the upper atmosphere, where
| the pressure is low, because they have low surface area per
| mass -- the atmosphere can stop them entirely. Their terminal
| velocity is low. (That is, when the velocity through air is
| high enough that the drag prevents gravity from speeding up the
| object any further.)
|
| Medium objects have a higher terminal velocity get deeper into
| the atmosphere before exploding. Fragments from these (which
| now have higher surface area per mass) can then be slowed
| further by the atmosphere and make it to the surface, but not
| so dramatically. Bits of the Chelyabinsk impactor fall into
| this category.
|
| Big objects have a high terminal velocity. They make it to the
| ground largely intact... and without being slowed as much by
| the atmosphere. That gives you craters and bad days for being a
| dinosaur.
| ddahlen wrote:
| I work on the NASA NEO Surveyor project (and have helped out a
| lot on the WISE/NEOWISE mission, which found a lot of asteroids).
| I create and run simulations of asteroid detections, which ends
| up being mostly orbit calculations. In the next few years the
| rate of detections of these sort of objects are going to go way
| up, NEO Surveyor and the Vera Rubin LSST telescopes are going to
| take our current knowledge of the solar system from about 1.4
| million asteroids to approximately 10x that. It is somewhat
| difficult to estimate how many we will see, since the size
| distribution follows a power law, and small changes in our
| estimates of the slope can be huge changes the number which
| exist.
|
| There are most likely hundreds of thousands to millions of a few
| meter sized asteroids flying around the inner solar system.
|
| I did a large chunk of the numerical analysis in this paper:
| https://arxiv.org/pdf/2310.12918
|
| I recommend figure 12 to get a sense of how far we can see at any
| given moment.
|
| The definition which is commonly used as "hazardous" is about a
| 140m asteroid, which would cause a _significantly_ bad day
| regionally, but not end civilization. That being said, 50m is
| still a very very bad day.
|
| These meter-ish size ones usually just make a pretty fireball.
|
| Some various links to data about this impact:
|
| https://cneos.jpl.nasa.gov/sentry/details.html#?des=2024%20R...
|
| https://minorplanetcenter.net/mpec/K24/K24R68.html
| nkrisc wrote:
| For anyone else curious who wants some tangible sense of the
| dangers, the Tunguska impactor is estimated to have been 50-60m
| in diameter [1]. The impactor that created the Barringer Crater
| in Arizona is estimated to have been about the same size [2].
|
| Regarding a 100m asteroid impact:
|
| > The pressure blast would destroy buildings up to 9 miles (15
| km) from ground zero, and windows would shatter more than 60
| miles away (100 km). To make matters worse, as the partially
| burned rock hit the ground, it would trigger seismic tremors
| that would spread through the planet's crust, carrying the
| destruction further away from the epicenter. The debris ejected
| into the air by the force of the impact would rain back on the
| ground miles away from the impact site, and the finer dust and
| dirt would remain hanging in the air, spreading with the wind
| across large distances.[3]
|
| I can imagine a 140m asteroid causing a very, very bad day
| indeed for a region.
|
| Not an expert, just curious and I can type stuff into a search
| engine.
|
| [1] https://en.m.wikipedia.org/wiki/Tunguska_event
|
| [2] https://en.m.wikipedia.org/wiki/Meteor_Crater
|
| [3] https://www.space.com/asteroid-apocalypse-how-big-can-
| humani...
| meowster wrote:
| I wonder, could an asteroid be traveling at a relative-to-
| Earth speed of very slowly, so that the impact most like just
| "setting down" on Earth rather than slamming into Earth?
| ianburrell wrote:
| There is minimum amount of energy from falling down Earth's
| gravity well. Earth escape velocity is 11 km/s. A big chunk
| of asteroid energy comes from Earth's gravity.
| seabass-labrax wrote:
| On the other hand, the orbital speed of Low Earth Orbit
| is 8km/s. Thus, with regard to asteroid redirection
| missions, we'd need 'only' about 3-4km/s of Dv to prevent
| this 'gently setting down' asteroid from hitting the
| Earth by capturing it into orbit.
|
| Definitely into science fiction territory here
| considering that DART resulted in a Dv measured in
| _centimetres_ per second, but I 'm still rather tickled
| by the idea of collecting a new moon for ourselves :)
| deepsun wrote:
| If we don't need to capture it to orbit, but just avoid
| hitting the Earth, centimeters might be enough. The trick
| is to be able to do it way in advance.
|
| Besides, why LEO? Even GSO is 11 times closer than the
| Moon.
| seabass-labrax wrote:
| You're quite right - attaining GSO would indeed require
| only another 3 or 4km/s. But it does seem a little unfair
| to put it in GSO; we'd surely want people in both
| hemispheres to get a chance to gawk at our new satellite!
| deepsun wrote:
| Taken that most of the Earth surface is empty uninhabited
| lands and oceans -- no biggie. Most probably.
| nkrisc wrote:
| Probably. Usually.
| kristjansson wrote:
| > 50m is still a very very bad day.
|
| Just to quantify the bad day scale: Tunguska[0] is estimated to
| have been 50-60m.
|
| [0]: https://en.wikipedia.org/wiki/Tunguska_event
| Teever wrote:
| I recently decided that I wanted to learn more about your
| field, so I set up a jupyter notebook and was perusing the
| available python libraries and I found this one[0] however it
| is apparently unmaintained.
|
| Can you suggest any beginner tools or resources for a layman to
| learn more about your field? I've taken an intro orbital
| mechanics course, solar system geology course and one on
| exoplanet detection and I'd like to keep the kinds of skills
| that I got from those courses fresh in my brain.
|
| How do you recommend I do that?
|
| https://docs.poliastro.space/en/stable/index.html
| ddahlen wrote:
| I am in the rather lengthy process of open sourcing a library
| for orbit propagation, but the previous art which is somewhat
| modern is the python rebound package. It's original design
| intent was for asteroid collision simulations, but it has
| been generalized a lot since then.
|
| Most of the state of the art in the field is algorithms from
| the 60s/70s, the classic software which many people use are
| packages like Mercury, written in either fortran or C++.
|
| These factors are why I am attempting to release my code to
| the (small) community.
| tabtab wrote:
| Small dinosaurs are very worried.
| steeeeeve wrote:
| This should be happening right now.
| 0x1ceb00da wrote:
| Visible from india. Not very prominent but clearly visible.
| phendrenad2 wrote:
| Did you see it?
| FartyMcFarter wrote:
| This is allegedly a video of the fireball:
|
| https://x.com/raymongdullana/status/1831378111453392958
| felideon wrote:
| That's quite a larger fireball than I was imagining. If I were
| in that general area and not given a heads up, I would have
| certainly freaked out.
| MeteorMarc wrote:
| Unfortunately, only one of the clips has a long enough duration
| to hear the start of the sonic booms, soundwaves from the
| detonations reaching the microphone.
| iJohnDoe wrote:
| Asteroid 2024 RW1, which was discovered just hours before its
| atmospheric entry, made a dramatic appearance over the
| Philippines on September 4, 2024. The asteroid, roughly the size
| of a small car (about 1 meter in diameter), was detected by the
| Catalina Sky Survey and was initially designated CAQTDL2 before
| being named 2024 RW1.
|
| The asteroid entered the atmosphere at a speed of approximately
| 11 miles per second (around 40,000 miles per hour) and burned up,
| creating a spectacular green flash visible to observers on the
| ground. Despite the cloud cover from Typhoon Yagi, the event was
| still visible and was captured on video by local residents.
|
| This event marks only the ninth recorded instance of an asteroid
| being detected before it impacted Earth.
| ddahlen wrote:
| We got enough data to get a rough estimate of its orbit before it
| hit:
| https://ssd.jpl.nasa.gov/tools/sbdb_lookup.html#/?sstr=2024%...
|
| Note though, this will likely have a huge range of uncertainty on
| it, as 8 hours of observation is not a lot.
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