
Scientists stunned by ‘city-killer’ asteroid that just missed Earth - swamp40
https://www.seattletimes.com/nation-world/scientists-stunned-by-city-killer-asteroid-that-just-missed-earth/
======
scraplab
I made a Twitter bot @lowflyingrocks, that tweets whenever something passes
close enough to note. If you find Twitter doesn’t offer you enough existential
dread already you might like it.

It scrapes the JPL data hourly, and it’s satisfying when it picks up these
close passes discovered at short notice:

[https://twitter.com/lowflyingrocks/status/115420008580852531...](https://twitter.com/lowflyingrocks/status/1154200085808525314)

~~~
number6
Ok little pet peeve of mine:

Every other time I hit some arbitrary Twitter limits of a post and 5 minutes
later I can access it.

At this point I believe it is to bully me into an account or using the app or
something.

I have a bunch of profanities in reply to this.

~~~
hansjorg
Are you using Firefox on Android? Using that I almost always get the rate
limit error. Never seen it otherwise.

~~~
JetSpiegel
You can bypass this by using the 'Request Desktop Site' checkbox.

Ironically, requesting the desktop site uses more bandwidth, defeating the
purpose of a rate limit.

~~~
kekebo
Resubmitting the url without the 'mobile' subdomain also works for me every
time for some reason. Same setup setup with Firefox on Android. It's
infuriating.

------
mkl
This is actually really common for smaller ones:

2015:
[https://en.wikipedia.org/wiki/List_of_asteroid_close_approac...](https://en.wikipedia.org/wiki/List_of_asteroid_close_approaches_to_Earth_in_2015)

2016:
[https://en.wikipedia.org/wiki/List_of_asteroid_close_approac...](https://en.wikipedia.org/wiki/List_of_asteroid_close_approaches_to_Earth_in_2016)

2017:
[https://en.wikipedia.org/wiki/List_of_asteroid_close_approac...](https://en.wikipedia.org/wiki/List_of_asteroid_close_approaches_to_Earth_in_2017)

2018:
[https://en.wikipedia.org/wiki/List_of_asteroid_close_approac...](https://en.wikipedia.org/wiki/List_of_asteroid_close_approaches_to_Earth_in_2018)

All the ones coloured red in the tables (the _majority_ ) weren't discovered
until after their closest approach.

------
tunesmith
"More than 90 percent of those (extinction-level) asteroids, which are 1
kilometer, 0.62 miles, or larger, have already been identified by NASA and its
partners."

How do they know it's 90%? I mean, if the denominator is unknown? If the
denominator is known, then doesn't that mean they've identified them?

~~~
mattkrause
Abundance estimation is a big problem in ecology (and other fields), and
they’ve developed some clever ways to estimate population sizes without doing
an exhaustive census.

One popular approach is a capture-recapture experiment. On your first trip,
you find as many of your targets as possible and mark each one. With turtles,
you might paint something on the shell; here, it might be something like
determining its orbit and other characteristics. You wait a bit, and search
again (starting from scratch), but this time you separately record the number
of “new” specimens and the number recaptured. A tiny bit of algebra from these
three numbers gives you an estimate of the population size.

~~~
joemag
It comes with a bias though, since your searches will bias towards finding
asteroids that are easiest to find using your search method.

~~~
BurningFrog
Seems like a bigger problem for turtles than for asteroids.

I mean, asteroids don't deliberately hide.

Sure, some are darker and/or have a less visible radar profile or whatever,
but the variations seem manageable.

~~~
craftyguy
They don't deliberately hide, but (as mentioned in the article) they can vary
dramatically in how visible they are to us over time if, for example, they
have a highly eccentric orbit.

------
Syzygies
It missed Earth by 73,000 kilometers; Earth has radius 6,371 kilometers.

(79371 * 79371) / (6371 * 6371) = 155.2

This was a game of darts in a galactic pub. The dart hit the dart board, but
not the bullseye (Earth). One in every 155 times we play this game, it ends
badly.

~~~
eridius
How does the math change when you take into account the fact that Earth exerts
a gravitational pull on the asteroid?

~~~
kryogen1c
Thinking out loud time! My favorite!

To matter for a single pass, the object must be small and/or traveling slowly.
Otherwise, itll just keep on cruising.

Iteratively is a different story. Many objects repeatedly cross earths path.
How that orbit changes over time i suppose is a function of the other gravity
wells the objects pass when they arent near earth. I expect there are so many
confounding gravities that only a certain belt\torus exists in the universe
where, inside that torus, space stuff is capable of running into us.

Side note: this article is clickbaity because it implies no one knew asteroids
almost crash into us without us knowing, but thats not true. People know.
There are hard reset buttons floating around in space and we might just press
one without warning.

[https://en.m.wikipedia.org/wiki/Potentially_hazardous_object](https://en.m.wikipedia.org/wiki/Potentially_hazardous_object)

~~~
probablybroken
Why would the size of the object matter in this instance?

~~~
kryogen1c
Mass, not really size. The smaller the object relative to earth, the more its
course is changed by earths gravity.

~~~
probablybroken
You may want to refer to Galileo's leaning tower of pisa experiment...

------
mturmon
You can browse recent approaches at:

[https://cneos.jpl.nasa.gov/ca/](https://cneos.jpl.nasa.gov/ca/)

To isolate to really near stuff, choose +/\- 30 days, and Nominal distance <=
1LD (lunar distance).

The asteroid in OP is linked to here:
[https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2019%20OK](https://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2019%20OK)
\-- there's an orbit diagram.

~~~
ratsmack
The interactive 3D orbital graphic is great for visualizing the orbits and how
they cross the Earth's path.

------
lisper
If this sort of thing concerns you, you might want to consider supporting this
organization:

[https://b612foundation.org](https://b612foundation.org)

~~~
projektfu
It's called B612 Foundation and not a single reference to the Little Prince on
the homepage besides the name? Weird.

~~~
lisper
Yeah, there is an explanation, but it's well hidden:

[https://b612foundation.org/ever-wondered-where-the-
name-b612...](https://b612foundation.org/ever-wondered-where-the-
name-b612-came-from/)

------
chris5745
I imagine without early and widespread warning, an asteroid impact could be
mistaken by nation-states for an attack. What safeguards (if any) might we
have or develop to prevent an asteroid hitting country 1 from causing a
“counter” strike by country 1 against country 2?

~~~
nvrspyx
Would country 1 counter-strike without getting confirmation that it was, in
fact, country 2? How would they know it wasn't country 3, 4, or 5?

~~~
tzakrajs
Similar to the cyber attack attribution problem, isn't it?

~~~
lowdose
Stuxnet had some pretty program time traces in the code.

------
jmkappz
JPL Horizons is awesome for this. You can easily obtain the information on
your own using the ephemerides at
[https://ssd.jpl.nasa.gov/horizons.cgi#top](https://ssd.jpl.nasa.gov/horizons.cgi#top)
:

\- minimum distance of 71350 km (44,334 miles vs 45,360 in article)

\- Speed around 24.5 km/s (15.2 miles/sec vs 15 in article)

\- Closest on july 25 at 01:21 UTC

Here's a rendering of the trajectory of the asteroid and the moon in july to
get an idea of how close it came (moon orbits around 384,000 km from earth):
[https://imgur.com/a/3JaakFJ](https://imgur.com/a/3JaakFJ)

------
ralphm
The original article ([https://www.washingtonpost.com/nation/2019/07/26/it-
snuck-up...](https://www.washingtonpost.com/nation/2019/07/26/it-snuck-up-us-
city-killer-asteroid-just-missed-earth-scientists-almost-didnt-detect-it-
time)) includes links to some interesting background information, including
the event leveling a huge forest area. And it correctly uses square km/miles
instead of "square acres".

------
pulkitsh1234
For those interested, you can watch Joe Rogan's podcast with Randall Carlson
on this topic:
[https://www.youtube.com/watch?v=R31SXuFeX0A](https://www.youtube.com/watch?v=R31SXuFeX0A)

------
partiallypro
The likelihood it would hit a highly populated area is still incredibly slim
even if it did strike earth. I wonder if there are some smaller asteroids on
rare occasions just landing in the ocean that we don't really know about.

~~~
mikhailfranco
The distribution of orbits, and hence strikes, is an interesting problem.

Here is a plot of population against latitude:

[https://www.themarysue.com/world-population-latitude-
longitu...](https://www.themarysue.com/world-population-latitude-longitude/)

I assume a bias to the ecliptic, hence the area within the tropics is more
likely to get hit. Big spikes for Jakarta, Dhaka, Shanghai/PRD,
Delhi/Mumbai/Karachi/Lahore, Kinshasa, Lagos ...

I also suppose you could attack the problem in two ways: historical strikes
(confounded by erosion, tectonics and subduction), and orbital statistics,
perhaps weighted by asteroid size.

Anyone have refs for this?

------
m0zg
So here's what I was wondering for quite some time: if, let's say,
hypothetically, there were an object approaching Earth at nearly the speed of
light, is there any way in our frame of reference to even detect it?

And is it possible for such an object to exist in our universe, and if not,
why?

The math seems to work out such that the object the size of a US quarter
(5.67g) at 0.999 C will have a relativistic kinetic energy around 2.6MT of
TNT.

~~~
Ididntdothis
If something travels nearly the speed of light we couldn’t detect it. Any kind
of information from this object would at maximum travel at the speed of light
so this information would arrive only a little sooner.

------
ycombonator
Asking for a friend, is it not possible to park phased array satellites out at
43,000 KM orbit looking for faint smaller asteroids with current technology?

~~~
rishav_sharan
Technically, yes. Politically? We don't use the word sense with politics.

------
simonebrunozzi
I might be wrong, but in a previous comment [0] a few days ago I noted that
the asteroid composition is mostly ice, which means it should be much less
dangerous than a "rock".

[0]:
[https://news.ycombinator.com/item?id=20508618](https://news.ycombinator.com/item?id=20508618)

~~~
xenonite
Similary, the Seattle Post writes:

> Lakdawalla said that while the asteroid’s close brush with Earth may have
> sparked some concern, “it is zero percent danger to us. It’s the kind of
> thing where you learn about something that you didn’t know about, like
> things flying close by us, and your inclination is to be scared,” she said.
> “But just like sharks in the ocean, they’re really not going to hurt you and
> they’re really fascinating to look at.”

------
ghostDancer
Planetary defense from Planetary Society if you want to help or participate
[http://www.planetary.org/explore/projects/planetary-
defense/](http://www.planetary.org/explore/projects/planetary-defense/)

------
jmiskovic
Sir Arthur Clarke describes the impact itself nicely in Rama intro:
[https://youtu.be/yMPA25SGlpA?t=88](https://youtu.be/yMPA25SGlpA?t=88)

As I understand, the mayor threat is the dust which doesn't settle for many
months. This could starve world's population and pose a major existential
risk. Maybe we can use our spy satellite network and just turn all sensors
outwards?

------
GarrisonPrime
I have no reason to doubt this story - that it caught everyone by surprise.
But if such an asteroid was discovered in advance and it was determined we
were at high risk of being hit, I'm not so sure the public at large would be
notified in every circumstance. If the impact would be large enough and/or the
warning short enough, getting people panicky might do more harm than good.

~~~
dandelany
The problem with this idea is that it rests on two incorrect assumptions -
that there is some governing body that would be able to prevent the release of
such information, and that we would immediately know upon detection that the
asteroid was on a collision course.

In fact, in this case, the asteroid was detected independently by the SONEAR
survey in Brazil and the ASAS-SN telescope network run by Ohio State
University. Neither of these would fall under the "jurisdiction" of NASA or
any governmental organization that would effectively be able to prevent them
from talking about it. ASAS-SN tweeted the discovery, and I'm quite sure they
didn't have to ask anyone permission to do so.

Secondly, the first few observations of a newly-discovered near-Earth object
are generally not enough information to calculate the object's orbit
accurately enough to know if it will hit Earth or not. So what do scientists
do when they discover one? They immediately report it to the IAU and get the
word out to as many other astronomers as possible, in order to obtain more
observations & accurately determine the orbit.

As a result, it's hard to imagine how such a discovery could be kept secret.

~~~
GarrisonPrime
>The problem with this idea is that it rests on two incorrect assumptions -
that there is some governing body that would be able to prevent the release of
such information, and that we would immediately know upon detection that the
asteroid was on a collision course.

Not necessarily. Only a couple people knew about this one before it had
whizzed by. While I agree it'd be impossible to keep an upcoming impact
secret, if the timeframe is short enough it would only take a few select
people to keep it contained long enough to no longer matter.

And choosing to keep it secret wouldn't only be done if collision was known to
be certain. Just having a moderate chance of impact might be enough.

------
shoo
on another hand, if you see a gamma-ray-burst heading this way, duck and
cover...
[https://www.youtube.com/watch?v=8HvwNOSnveE](https://www.youtube.com/watch?v=8HvwNOSnveE)

~~~
thatswrong0
I mean that’d be near instant vaporization wouldn’t it? For some reason that
makes me less scared about it since you wouldn’t really know what’s happening
before it’s all over

~~~
omegaworks
No, according to the video gamma ray burst means increase in UV potentially
damaging DNA of phytoplankton, global cooling due to NO2 solar energy
reflection.

It'll be pretty slow, but at a large scale.

~~~
r3dk1ng
Your comment made me think of whether a GRB could have caused the cambrian
explosion. So I searched for that and found this paper:

[https://arxiv.org/abs/1403.7303](https://arxiv.org/abs/1403.7303)

------
mikhailfranco
I am surprised with the talk about optical visibility. Are there no radars
deployed for scanning the skies?

~~~
scarhill
Because these objects are moving fast, you would need to look a long way out.
Long range radar is hard because the inverse square law applies in both
directions, so you need 16x the power to double the range.

~~~
mikhailfranco
Maybe a solar powered array on the dark side of the Moon, to restrict any
interference from Earth systems, and you get a nice sweep of the ecliptic for
free.

------
aasasd
So it was set to stun, not to kill?

------
AtomicOrbital
duplicate thread see
[https://news.ycombinator.com/item?id=20537941](https://news.ycombinator.com/item?id=20537941)

------
known
Doesn't it vindicate the we need to weaponize space?

~~~
skyfaller
Not really, because space weapons inevitably lead to at the very least space
weapons testing, and most likely space combat. Space combat creates space
junk, which prevents us from going to space in the future, which prevents us
from detecting and deflecting asteroids.

You might think "well, we just need to find ways to destroy space junk" but
unfortunately (almost?) all tools useful for destroying space junk can also be
used to destroy perfectly functional objects in space, and therefore count as
space weapons, which lead to space junk...

------
torgian
I still think someone tried to redirect its path and made a minor mistake in
their calculations ;)

------
dv_dt
It's too bad the "space force" isn't setup just for this.

~~~
hdfbdtbcdg
Scientists are already searching for and tracking such objects. More funding
would be nice but we definitely don't need the US to break more treaties in
order for the world to track NEOs.

~~~
antepodius
Who really cares about the space treaty?

It'd be nice to have a well-funded group that has 'making sure no asteroids
hit us' as part of its motto

~~~
hdfbdtbcdg
Russia and China would create a space force if the US did...

~~~
dv_dt
Maybe we should create a world anti-asteroid space force...

------
phkahler
An asteroid on collision course will not be seen. I just realized an old
concept applies here. When two objects are on a collision course with each
traveling in a straight line, the apparent heading toward one as viewed from
the other does not change. In other words, when a deer runs in front of a car,
the angle to the deer doesn't change - it just gets bigger as you close in,
but position in your field of view doesn't change.

Astronomers look for things moving against the background sky, but over a
short enough time span (maybe a few days) the earth and an asteroid are moving
almost in straight lines. That means all you'd see is a speck of light that
gets brighter as it gets closer, but does not appear to move against the
distant background stars.

Has anyone quantified this phenomenon with respect to asteroid hunting?

~~~
Smithalicious
This would be true if the asteroid and the earth are both points. Obviously,
they aren't. An observing scientist would not see it this way unless it were
heading directly for them.

~~~
phkahler
>> An observing scientist would not see it this way unless it were heading
directly for them.

That was my point exactly. An asteroid heading directly towards us will not
appear to be moving against the background. If that movement is required in
their detection methods, it will fail for the most dangerous ones.

