Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Asteroid ZTm0038 with a >3% impact probability

newton.spacedys.com

Post reply on HN
Print view View original

181–190 of 252 posts

Re: Asteroid ZTm0038 with a >3% impact probability

#181

Post by mabbo »

Karellen wrote: post #162
mrb wrote: post #130

Earlier quoted context omitted.

I can answer 2 of your questions: - What is the probability that this asteroid will hit us? It's listed in the article: Impact probability 0.034, meaning 3.4% chance of impact. - What is the time interval where that probability applies? It's also listed: impact was estimated to potentially occur between 2023/08/14 04:48 TDB and 2023/08/15 12:22 TDB. (TDB seems to be UTC time without leap seconds? not sure). In other…

TDB: https://en.wikipedia.org/wiki/Barycentric_Dynamical_Time > [TDB] is a relativistic coordinate time scale, intended for astronomical use as a time standard to take account of time dilation when calculating orbits and astronomical ephemerides of planets, asteroids, comets and interplanetary spacecraft in the Solar System. TDB is now (since 2006) defined as a linear scaling of Barycentric Coordinate Time (TCB). A f…

It seems pedantic, but I'll bet the differences matter when you're talking about objects that have relative speeds in the tens of km per second.

2ms at 10km/s is off by 20m.

Re: Asteroid ZTm0038 with a >3% impact probability

#182

Post by DouweM »

pdabbadabba wrote: post #177
Leary wrote: post #132

Earlier quoted context omitted.

Found this tweet with an impact probability map that is around northern US/Asia/Europe : https://twitter.com/JoelSercel/status/1691549821629526219 "If it is real this IS the worst asteroid threat ever discovered and the impact location and times are ugly (will post pics shortly). Note that the impact is in the next couple days! However, an Italian colleague of one of our astronomers suspects there is an error in the…

What should we make of the fact that this tweet has since been deleted?

With this retraction at https://x.com/joelsercel/status/1691588629079138391:

> I would like to make an apology to the small body community. Some information was shared with me on an internal company message board that I did not have full perspective on and I posted a tweet, which I now understand was not appropriate. It was preliminary data and I did not have full perspective on it.

“Preliminary data” is not very reassuring.

Re: Asteroid ZTm0038 with a >3% impact probability

#183

Post by jacquesm »

MauranKilom wrote: post #166
cfraenkel wrote: post #154

Earlier quoted context omitted.

It's not a model that is poorly calibrated - you seem to be taking a software-centric concept far away from where it's useful. The uncertainty at initial observation is because when you first observe an object, you only have observations covering a tiny bit of the orbit, resulting in very wide error bars. The "model" (Newtonian orbital dynamics) is one of the most precise models we have. Doesn't help when the observa…

Unless one in every 33 asteroids that have 3% impact probability at some point in time actually impacts earth, there is clearly some unwarranted assumption in the error bar/distribution calculation. "The measurement data has noise" does not explain why the noise has a bias towards "the asteroid will hit earth" whereas reality so far has been biased towards "the asteroid will not hit earth". (This assumes that signifi…

That's because Earth has gravity, and an asteroid that comes close enough can get deflected onto the planet even if right now it seems to be on a trajectory to miss it entirely. The closer they get and the lower the relative speeds the larger the chance that they will collide and that's not a linear relationship. Beyond a certain boundary impact is certain, then the question is what the time of the impact is and how precise the observations up to that point are in order to figure out where and when exactly it will come down. That won't happen very long before the impact itself happens even if you could say some time in advance roughly in which hemisphere and roughly when. But not precise enough to be very useful.

Re: Asteroid ZTm0038 with a >3% impact probability

#184

Post by ortusdux »

killthebuddha wrote: post #100

I'm having a weirdly difficult time finding some basic ELI5 answers. - What is the probability that this asteroid will hit us? - What is the time interval where that probability applies? - Do we have a probability distribution for where it might hit? I don't know anything about anything, but I assume we know what *general direction* it's coming from? - Do we have a probability distribution for the potential blast rad…

I found this breakdown of JPL's CNEOS data to be every helpful. The close approach time chart shows % chance of impact vs day. From this I take it that we just didn't have enough info at the time of publishing.

Re: Asteroid ZTm0038 with a >3% impact probability

#185

Post by jacquesm »

noduerme wrote: post #173
MauranKilom wrote: post #166

Earlier quoted context omitted.

Unless one in every 33 asteroids that have 3% impact probability at some point in time actually impacts earth, there is clearly some unwarranted assumption in the error bar/distribution calculation. "The measurement data has noise" does not explain why the noise has a bias towards "the asteroid will hit earth" whereas reality so far has been biased towards "the asteroid will not hit earth". (This assumes that signifi…

One explanation would be the Anthropic Principle. In 3% of universes you were killed today, you're just not living in one of those.

In 97% of the universes dinosaur descendants rule planet earth. But on this one they got unlucky.

Re: Asteroid ZTm0038 with a >3% impact probability

#186

Post by oskarkk »

lucb1e wrote: post #114
lijok wrote: post #112

Earlier quoted context omitted.

Can you elaborate on the question you're asking?

Put differently: am I missing something if I say this website is similar in function to https://hasthelargehadroncolliderdestroyedtheworldyet.com ? At least in terms of a public service announcement; I understand it's interesting for science but not so much for linking "hey look there's an X% chance of impact....yesterday!" on news websites

I find it very interesting even if the approach was yesterday, as the chances were seemingly quite high and asteroid was quite big. Also, Hacker News isn't exactly only news, just any interesting things, current or past.

Re: Asteroid ZTm0038 with a >3% impact probability

#187

Post by msandford »

MauranKilom wrote: post #166
cfraenkel wrote: post #154

Earlier quoted context omitted.

It's not a model that is poorly calibrated - you seem to be taking a software-centric concept far away from where it's useful. The uncertainty at initial observation is because when you first observe an object, you only have observations covering a tiny bit of the orbit, resulting in very wide error bars. The "model" (Newtonian orbital dynamics) is one of the most precise models we have. Doesn't help when the observa…

Unless one in every 33 asteroids that have 3% impact probability at some point in time actually impacts earth, there is clearly some unwarranted assumption in the error bar/distribution calculation. "The measurement data has noise" does not explain why the noise has a bias towards "the asteroid will hit earth" whereas reality so far has been biased towards "the asteroid will not hit earth". (This assumes that signifi…

Imagine you see a car 1 mile away as you're preparing to cross the street. 1 sec later, it's a bit closer. You wonder "will this car hit me?". It's hard to say since the car is so far away and your measurements of its speed are so poor.

You wait 5 sec and it's still only imperceptibly closer. You realize there is no way it could possibly hit you. You cross the street unconcerned.

Re: Asteroid ZTm0038 with a >3% impact probability

#188

Post by radicaldreamer »

DouweM wrote: post #182
pdabbadabba wrote: post #177

Earlier quoted context omitted.

What should we make of the fact that this tweet has since been deleted?

With this retraction at https://x.com/joelsercel/status/1691588629079138391 : > I would like to make an apology to the small body community. Some information was shared with me on an internal company message board that I did not have full perspective on and I posted a tweet, which I now understand was not appropriate. It was preliminary data and I did not have full perspective on it. “Preliminary data” is not very re…

Pretty concerning update imo ^^

Re: Asteroid ZTm0038 with a >3% impact probability

#189

Post by Enginerrrd »

onlyrealcuzzo wrote: post #160
mrb wrote: post #130

Earlier quoted context omitted.

I can answer 2 of your questions: - What is the probability that this asteroid will hit us? It's listed in the article: Impact probability 0.034, meaning 3.4% chance of impact. - What is the time interval where that probability applies? It's also listed: impact was estimated to potentially occur between 2023/08/14 04:48 TDB and 2023/08/15 12:22 TDB. (TDB seems to be UTC time without leap seconds? not sure). In other…

Probability without confidence interval is not very useful. If there's <1% confidence - this is not exactly news.

The probability takes into account the error on the measurements so I'm not sure what you're getting at

Re: Asteroid ZTm0038 with a >3% impact probability

#190

Post by mazlix »

harwoodr wrote: post #145

Pretty graphs of possible impact sites: https://twitter.com/JoelSercel/status/1691549821629526219

That tweet which had an image showing bands of latitude that it may hit and times (london/newyork ish tomorrow and day after) has been deleted by the author and now says "I would like to make an apology to the small body community. Some information was shared with me on an internal company message board that I did not have full perspective on and I posted a tweet, which I now understand was not appropriate. It was preliminary data and I did not have full perspective on it."

I don't feel very reassured.

Post reply on HN