
Bright Explosion on the Moon - ColinWright
http://science.nasa.gov/science-news/science-at-nasa/2013/16may_lunarimpact/
======
motoford
I saw this once. It was quite a few years back, through my 8" dob in my front
yard. I saw a flash and couldn't imagine what it could have been except an
impact.

After some research online that night I began to doubt myself, most people
concluded it was too rare and would not be visible.

The next day I saw someone asking in a newsgroup about the mysterious flash he
had seen the night before while observing the moon through his telescope.
Again, the general consensus was that he couldn't have seen an impact, it was
too rare and would not be visible.

I checked with him and we both saw the flash at the same time.

I also saw a satellite transit the moon once with that same telescope, it was
so cool.

And to think I don't even pull it out anymore. Sad....

~~~
sigmavirus24
You know what you must do now. Pull that sucker out and start looking at the
skies again, with your kids too if you have them.

~~~
blantonl
well, if he doesn't pull out - he will be grateful in a few months to have
kids to share his discovery.

------
pydanny
Just wanted to say that I helped build this site. It's 2009/2010-era Django
site built on feincms with a PostgreSQL backend.

Originally it was a Plone site but after a year we realized it was too hard to
meet the deadlines of NASA VIPs. So we moved it to Django. Also, myself and
the other developers have NEVER been happy with the flash on the front page.
:P

~~~
acdha
I would be remiss in not thanking the Varnish cache developers, too: it's
using CloudFront now but Varnish came in quite handy when we suddenly jumped
from mostly images to some large videos like [http://science.nasa.gov/science-
news/science-at-nasa/2010/21...](http://science.nasa.gov/science-news/science-
at-nasa/2010/21apr_firstlight/) shortly after launch.

The scariest bit of code was probably the scraper + html5lib normalizer I used
to migrate something like 15 years of legacy static HTML content from two
separate into the CMS using a large pile of selectors and cleanup heuristics.

[http://chris.improbable.org/2009/10/16/deploying-django-
site...](http://chris.improbable.org/2009/10/16/deploying-django-sites/)
describes how the site was packaged using RPM so we could fit within the more
traditional IT model used by the production sysadmins.

One open-source tool which came out of this was
<https://github.com/shentonfreude/webcompare> which we used to bulk-compare
the old and new sites to confirm that all of our legacy URLs either redirected
or were intentionally 404/410ed.

~~~
pydanny
Thanks for speaking up! FWIW, you did most of the work for the migration and
rebuild. I apologize for not naming you when most of this was your work. :-)

~~~
acdha
No apology necessary - I find it feels weird to name people unless they're
already part of the conversation.

------
rkaplan
I found the footnote particularly interesting:

"The Moon has no oxygen atmosphere, so how can something explode? Lunar
meteors don't require oxygen or combustion to make themselves visible. They
hit the ground with so much kinetic energy that even a pebble can make a
crater several feet wide. The flash of light comes not from combustion but
rather from the thermal glow of molten rock and hot vapors at the impact
site."

~~~
lutorm
Combustion doesn't make things explode; it just heats things up so they
vaporize. But there are other ways to heat things up, too, and the end result
is the same.

I thought it was a weird footnote. I mean, do people really think that the
rock would burn even if there was oxygen?

~~~
Retric
I suspect many meteors can and will combust. Lot's of things love oxygen bonds
once they get enough energy and there is not a lot oxygen or heat in space.

PS: Think Class D Fire <http://en.wikipedia.org/wiki/Fire_classes>

------
fractallyte
Back in 1982, I saw a very bright flash on the Moon - naked eye! It was early
Sunday morning (5.22 am) on July 18th.

To this day, I'm not sure what caused it, and I've always eagerly followed up
on any reports of 'transient Lunar phenomena', or, as in this instance,
'bright explosions'.

I once spoke to Patrick Moore about it, with a full description (I remember
him asking if it was summer time - yes, it was). He was similarly intrigued,
and promised to look into it, but I never managed to follow up...

------
scottshea
And that ladies and gentlemen is why having an atmosphere is a very good
thing.

~~~
ghshephard
I wonder if the meteorite that exploded in the atmosphere over Russia did more
or less damage than if it had struck the earth intact.

Clearly Atmosphere makes a good shield for burning up the small meteorites -
but I wonder if it exacerbates the damage from medium sized ones?

~~~
InclinedPlane
Had that impact hit the ground it would have released over 100 kilotons of
energy. It would have been far, far more destructive and deadly.

~~~
jlgreco
But without an atmosphere the shockwave from that 100 kiloton explosion should
be pretty minimal (through the ground only), and any debris flung into the
atmosphere would fall right back down on parabolic trajectories (or go into
orbit), not linger in the sky for months/years.

The danger posed by such an explosion, off the top of my head, would be
getting hit by the object itself, getting hit by falling debris ejected by the
explosion, structural damage from the shockwave that traveled through the
ground... I'm not sure what else.

Of course without an atmosphere everyone would be dead anyway, so I suppose
this is kind of a silly thing to think about.

~~~
danbruc
_Of course without an atmosphere everyone would be dead anyway, so I suppose
this is kind of a silly thing to think about._

Just never walk out of your front-door without wearing your space suit.

~~~
jlgreco
Hmm. Living in pressure vessels makes structural damage to buildings a great
deal more dangerous.

------
WA
In the video on the website:

    
    
      Date: US date format
      Weight: metric
      Size: metric
      Speed: imperial
      Explosion: metric
    

Consistency is key.

~~~
samwillis
Well NASA has history with making $300 million mistakes with units of mesure:

[http://en.wikipedia.org/wiki/Mars_Climate_Orbiter#Cause_of_f...](http://en.wikipedia.org/wiki/Mars_Climate_Orbiter#Cause_of_failure)

    
    
      The primary cause of this discrepancy was engineering error. 
      Specifically, the flight system software on the Mars Climate 
      Orbiter was written to take thrust instructions using the 
      metric unit newtons (N), while the software on the ground that 
      generated those instructions used the Imperial measure 
      pound-force (lbf). This error has since been known as the 
      "metric mixup" and has been carefully avoided in all missions 
      since by NASA.

------
chiph
I think the guidance about how deep you have to bury a moon base to be safe
just got revised.

Cosmic rays? Nope - it's the meteors you really have to watch out for.

------
Zimahl
Can someone explain to me why this would be bright? I understand that this
should send up a fair amount of ejecta but wouldn't most of the light be just
from a reflection of the sun off of the particles?

If so, this isn't much of an explosion - it's just the most significant impact
we've seen so far. I guess explosion is more interesting to the every-man.

~~~
duskwuff
Read rkaplan's comment above. In short, it's hitting with so much energy that
the force of the impact alone is enough to leave the rock glowing-hot.

~~~
herdrick
And even vaporize some of the material, thus an explosion.

------
techas
"Lunar meteor showers have turned out to be more common than anyone expected"

what does that mean? Is there more stuff flying through space than we thought?
Does this have some consequence in the odds of hitting something in space?

------
yutyut
It's remarkable to me that someone peering up at the moon right when this
struck could have noticed the flash.

~~~
deletes
It wasn't noticed live, the moon was recorded with the help of a telescope and
the explosion was noticed later by an analyst. I also doubt anyone could see
that explosion without a telescope as the moon itself is quite bright.

~~~
mapmeld
In the video, the narrator says that someone looking at the moon would have
seen it, even without a telescope.

------
lifeisstillgood
The Moon - it's like have BatWings of steel to protect us from evil.

------
yashg
It seems Decepticons have landed on the moon!

------
WalterBright
Soon, there will be Brights everywhere!

------
alexmcroberts
oh gawd, transformers has started...

~~~
electronous
oh gawd, reddit is leaking...

~~~
saraid216
Aaaand obligatory,

> If your account is less than a year old, please don't submit comments saying
> that HN is turning into Reddit. (It's a common semi-noob illusion.)

<http://ycombinator.com/newsguidelines.html>

