
A meteorite hit the moon during yesterday's total lunar eclipse - curtis
https://www.newscientist.com/article/2191526-a-meteorite-hit-the-moon-during-yesterdays-total-lunar-eclipse/
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scrumbledober
Scott Manley did a great quick video about this

[https://www.youtube.com/watch?v=Smp7TqccTpY](https://www.youtube.com/watch?v=Smp7TqccTpY)

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gibolt
After watching the video, I feel like there should be software that gets
regular updates of planetary surfaces and highlights drastic changes.

Probably exists somewhere, but would be neat to see historical changes

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dotancohen
If you can persuade some congressional committee to fund NASA to develop,
launch, and maintain the probes then I'm sure you'll find no shortage of
people willing to pay the taxes for it all.

I happen to agree with you, and would be happy to see taxes allocated towards
further exploration of the solar system. But resources are limited.

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geggam
If only we got to choose what to pay taxes for...

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ajuc
In Poland you can choose one non-profit organization to pass 1% of your taxes
for last year. If you choose nothing it goes to the state budget.

It's a nice idea, even if some organizations abuse it (they give out free tax-
filling software that has their organization hardcoded).

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baud147258
It doesn't work exactly this way in France, but any donation to a registered
non-profit gets you a 66% rebate of that amount to your income taxe (within a
20% limit of your taxable income).

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ajuc
Yeah, it's the same in the result, but the barrier of entry is significantly
lower (easier to fill 1 field in tax form once a year than to make a payment
and then get a refund).

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baud147258
> get a refund

We don't get a refund (perhaps I misused a word in my last comment): when
filling my tax, there's a box for amount donated, which is then used when
calculating the amount of money I'll have to pay as taxes.

But yeah, the barrier is higher, but I think the choice of organizations is
wider in our case, like the organization to which I gave money the last two
years wouldn't be on the list for example.

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sizzzzlerz
I know its just a coincidence that the meteor hit during a lunar eclipse while
millions of people might have been watching (and probably not seeing it). But,
it gives me chills to think that lump of rock has been orbiting through the
solar system for possibly billions of years with its unknown fate already
sealed. All it took was for the Sun and all the planets and moons to go
through their cycles an uncountable number of times to bring it to its
ultimate conclusion.

Now, unknown asteroid, your watch is done.

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jessriedel
> for possibly billions of years with its unknown fate already sealed

Probably not for quite that long. The path of a meteor is only going to be
deterministic on a timescale given roughly by the largest Lyapunov exponent
associated with its orbit. On longer timescales, even the very tiny
irreducible quantum uncertainty in its initial state would be enough to cause
it to miss the Moon.

Not sure what the Lyapunov time is for these meteors, but typical time scales
for planets are 2M-200M years. For small things like meteors, there are likely
other sources of noise (e.g., solar wind pressure) with quantum uncertainty
that lead to non-determinism even faster.

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nonbel
> _" The path of a meteor is only going to be deterministic on a timescale
> given roughly by the largest Lyapunov exponent associated with its orbit. On
> longer timescales, even the very tiny irreducible quantum uncertainty in its
> initial state would be enough to cause it to miss the Moon."_

My understanding is that chaotic systems are still deterministic, the state at
some later time is just very sensitive to the initial conditions (which it may
be impossible to know with much precision). "Irreducible quantum uncertainty"
is something else that has nothing to do with Lyapunov time.

I also see Lyapunov died in 1918,[1] while the uncertainty principle was
introduced in 1927.[2]

[1]
[https://en.wikipedia.org/wiki/Aleksandr_Lyapunov](https://en.wikipedia.org/wiki/Aleksandr_Lyapunov)
[2]
[https://en.wikipedia.org/wiki/Uncertainty_principle](https://en.wikipedia.org/wiki/Uncertainty_principle)

~~~
Someone
_”the state at some later time is just very sensitive to the initial
conditions”_

I am sure it has zero impact in practice, but theoretically, there’s a random
component that isn’t part of the initial conditions.

Our current understanding of radioactive decay is that it is 100% random, and
that the law of conservation of momentum also holds at quantum scale. If so,
radio-active decay that emits a particle that escapes from an orbit around the
meteor (relatively easy, given the lack of atmosphere and low mass of the
meteor) has a (minute) random effect on the velocity vector of the remaining
larger part.

Because individual decay events are uncorrelated, adding up all the effects of
radio-active decay over time will make the already extremely tiny effect a lot
smaller (by the square root of the number of decays, if I’m not mistaken, but
there may the timing of decays gives earlier decays a larger effect on the
eventual course, so it may be slightly less dramatic).

That’s why I doubt it has any practical impact.

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tomp
> Our current understanding of radioactive decay is that it is 100% random

Isn't it only _locally_ random? I.e. there could still be some global "initial
conditions" that make it deterministic (yet unknowable for us)... As in, given
a sequence of numbers, there's no way to tell if it was generated randomly or
just pseudorandomly (e.g. by RSA/SHA).

~~~
db48x
That would be called a "hidden variable", and it's already proved that no
theory involving hidden variables can be correct.

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wizzard
> The so-called “super wolf blood moon” was eagerly watched by millions of
> people around the world, mostly via live streaming video.

How do they know most people watched via live stream as opposed to just
looking out the window or a telescope?

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gowld
It was visible from all of North and South America, and Western Europe, so
most people couldn't see it.

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wizzard
Even if millions of people from Asia and Australia were interested enough to
watch a live stream of it, I don’t believe they can categorically state that
the majority of the people on the entire planet watched via live stream.

I’m mostly arguing because I find the idea of everyone watching the eclipse on
a video screen kind of sad.

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Already__Taken
Why, I got up in the UK, found it cloudy and went back to bed. That I could
have streamed it live is amazing if you think about it.

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Syzygies
Wouldn't a meteorite impact be even more visible in the dark part of a new
moon? Why did researchers go out of their way to observe one during a lunar
eclipse?

(In elementary school during NASA's Mercury program, a joke made the rounds
that a certain Eastern Bloc country's space program would land on the Sun by
"flying at night".)

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dylan604
Yes, the new moon is when they are most active, however, one of the guys in
the program specifically has been trying to see an impact during an eclipse
for quite some time now. The shadow of the Earth causes the new moon phase,
and it is the same shadow that causes the eclipse. Why wouldn't they take the
free bonus 2ish hours of dark moon time to search?

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davidmurdoch
Meteorites aren't more active during a new moon; they're just easier to see.

The shadow of the Earth does not cause the new moon phase. If it did, it'd be
a lunar eclipse.

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swebs
Did the impact produce light, or was that kicked-up dust reflecting sunlight?

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jelliclesfarm
“Agent”!!! Seveneves by Neal Stephenson!

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bitwize
So it was a SuperBloodWolfMeteorImpactMoon. Awesome.

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diggernet
Looking forward to high resolution before and after photos from LRO.

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ttonkytonk
Anybody know what time the strike occurred?

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sp332
04:41:43 UTC
[https://www.reddit.com/r/space/comments/ai79zy/possible_mete...](https://www.reddit.com/r/space/comments/ai79zy/possible_meteor_impact_on_moon_during_the_eclipse/)
and
[https://twitter.com/chrfrde/status/1087532344909676545](https://twitter.com/chrfrde/status/1087532344909676545)

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bsherrill
I’m curious are we sure it was an asteroid that hit the surface?

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LandR
As opposed to ?

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demarq
still amazed something the size of a football could cause that

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cpeterso
This story reminded me of Neal Stephenson's 2015 novel _Seveneves_ , where the
Moon, struck by some unknown object, breaks apart. Most life on Earth is
destroyed except for a few thousand people who can escape. Humanity has one
year to prepare civilization for 5000 years in orbit before they can safely
return to Earth again. Very interesting thought experiment on the
technological and genetic outcomes!

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

~~~
quizme2000
Spoiler Alert! Yes in the first pages there is a moon event, the rest of your
comment just gives away the plot.

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cmpaul
Agreed, could probably have avoided giving away the plot here. The book is
definitely worth the read!

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cpeterso
I see what you mean, but I don't think I gave away too much of the plot. The
back of the book itself provides all those same details, other than the word
"Moon" which is revealed in the first sentence of the book.

[https://images-na.ssl-images-
amazon.com/images/I/515blU3eIzL...](https://images-na.ssl-images-
amazon.com/images/I/515blU3eIzL.jpg)

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detritus
I have this book on my shelf to read and, as with most books, I try not to
read synposes or cover details in advance, preferring instead to have it be as
much of an unknown journey as possible, so ... thanks for giving away what
sounds like a fundamental part of the book and arguing against perhaps editing
your original post.

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cpeterso
FWIW, I would edit or remove my original comment to remove spoilers but HN no
longer allows me to edit that comment.

Also, there was a study that showed spoilers actually _increase_ readers'
enjoyment (except for mystery books):

[https://www.universityofcalifornia.edu/news/spoiler-alert-
sp...](https://www.universityofcalifornia.edu/news/spoiler-alert-spoilers-
make-you-enjoy-stories-more)

