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Watsisname
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25 Nov 2020 07:00

The Apollo 14 astronauts might have found an Earth meteorite on the Moon. :)

Terrestrial-like zircon in a clast from an Apollo 14 breccia

Also a good paper to read: On the Survivability and Detectability of Terrestrial Meteorites on the Moon.
 
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midtskogen
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25 Nov 2020 07:17

Watsisname wrote:
Source of the post Also a good paper to read: On the Survivability and Detectability of Terrestrial Meteorites on the Moon.

Interesting, but it doesn't seem to cover the survivability of biomarkers in rocks ejected from Earth.  So what's the worst shock: being hit and ejected into space from Earth, or hitting the lunar surface?
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25 Nov 2020 08:26

midtskogen wrote:
Watsisname wrote:
Source of the post Also a good paper to read: On the Survivability and Detectability of Terrestrial Meteorites on the Moon.

Interesting, but it doesn't seem to cover the survivability of biomarkers in rocks ejected from Earth.  So what's the worst shock: being hit and ejected into space from Earth, or hitting the lunar surface?

I would think the force necessary to being hit and ejected into space from Earth is worse
 
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25 Nov 2020 08:28

Watsisname wrote:
The Apollo 14 astronauts might have found an Earth meteorite on the Moon. :)

Terrestrial-like zircon in a clast from an Apollo 14 breccia

Also a good paper to read: On the Survivability and Detectability of Terrestrial Meteorites on the Moon.

wow what a discovery!
 
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25 Nov 2020 17:14

midtskogen wrote:
Source of the post So what's the worst shock: being hit and ejected into space from Earth, or hitting the lunar surface?

Good question. I don't think it's an easy answer. I expect both are pretty bad shocks, and going from Earth to Moon is worse on both sides than going from Moon to Earth, since the Moon lacks an atmosphere to slow them down, and fragments will strike the surface at at least 2.3km/s. But that might not be as bad as it sounds, since the shock can be reduced by impacting the loose regolith and at a shallow angle. (Newton's impact depth approximation again being useful here.) Fragments striking the Moon won't be totally vaporized, though they are probably shattered quite badly. I'd expect just small pieces to survive. On top of that, you then have to worry about the slow but steady erosion from micrometeorite bombardments.

So I wouldn't expect to find large terrestrial meteorites on the Moon, but more likely very tiny fragments that got buried and protected under the regolith, then compactified into a new rock by an impact (forming a breccia), and then ejected to the surface by another impact in more recent history so that it could be discovered. Expect terrestrial meteorites on the Moon to mostly be found as clasts, perhaps even a clast within a clast within a rock. Biomarkers would probably limited to chemical evidence, maybe single cellular structures if we're very lucky. (But most transfer of material from Earth to Moon happened a long time ago when there was no multicellular life, anyway.)

I did joke a while back that there might be tiny bits of dinosaur bone on the Moon, though good luck finding them. :P
 
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26 Nov 2020 03:01

Watsisname wrote:
midtskogen wrote:
Source of the post So what's the worst shock: being hit and ejected into space from Earth, or hitting the lunar surface?

Good question. I don't think it's an easy answer. I expect both are pretty bad shocks, and going from Earth to Moon is worse on both sides than going from Moon to Earth, since the Moon lacks an atmosphere to slow them down, and fragments will strike the surface at at least 2.3km/s. But that might not be as bad as it sounds, since the shock can be reduced by impacting the loose regolith and at a shallow angle. (Newton's impact depth approximation again being useful here.) Fragments striking the Moon won't be totally vaporized, though they are probably shattered quite badly. I'd expect just small pieces to survive. On top of that, you then have to worry about the slow but steady erosion from micrometeorite bombardments.

So I wouldn't expect to find large terrestrial meteorites on the Moon, but more likely very tiny fragments that got buried and protected under the regolith, then compactified into a new rock by an impact (forming a breccia), and then ejected to the surface by another impact in more recent history so that it could be discovered. Expect terrestrial meteorites on the Moon to mostly be found as clasts, perhaps even a clast within a clast within a rock. Biomarkers would probably limited to chemical evidence, maybe single cellular structures if we're very lucky. (But most transfer of material from Earth to Moon happened a long time ago when there was no multicellular life, anyway.)

I did joke a while back that there might be tiny bits of dinosaur bone on the Moon, though good luck finding them. :P

What about something even more rare..... a rock making it from the Earth to Mars.  That might raise some biocontamination concerns if it ever did happen......  Since rocks have made it from Mars to Earth the reverse should at least theoretically be possible.
 
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28 Nov 2020 14:22

Another big one near Sweden: http://norskmeteornettverk.no/bilder/2020/ildkule-20201128.mp4

Again the best videos were from Norway, though mostly cloudy here.  But any meteorites fell into the sea this time.
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29 Nov 2020 08:16

midtskogen wrote:
Another big one near Sweden: http://norskmeteornettverk.no/bilder/2020/ildkule-20201128.mp4

Again the best videos were from Norway, though mostly cloudy here.  But any meteorites fell into the sea this time.

I heard there are some amazing northern lights displays going on over there!
 
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29 Nov 2020 10:51

A-L-E-X wrote:
Source of the post I heard there are some amazing northern lights displays going on over there!

Amazing, yes, in northern Scandinavia, but that's normal.

More videos of yesterday's fireball (check the full moon in some videos to get a sense of the brightness): http://norskmeteornettverk.no/bilder/2020/videos-20201128.mp4
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29 Nov 2020 11:35

Wow, would you say that fireball is brighter than -11 (the brightness of the full moon), it looks like maybe -13 to me!
 
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29 Nov 2020 12:45

A-L-E-X wrote:
Source of the post Wow, would you say that fireball is brighter than -11 (the brightness of the full moon), it looks like maybe -13 to me!

I haven't tried to estimate, but it's way brighter than than -13.  More like -17 or even -18, though briefly.  Meteors brightness is usually normalised to the brightness as seen from 100 km distance.  All the videos are from greater distances.
A loud bang was heard near the coast north of Gothenburg.  It made big news in both Sweden and Norway yesterday.  I think I got about 7 phonecalls from Swedish journalists.
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30 Nov 2020 00:57

It's amazing both how rapid and bright that final flash is!  Looking forward to getting more stats on the meteor (speed, angle, initial orbit?) if/when they're determined.
 
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30 Nov 2020 05:27

Watsisname wrote:
Source of the post  Looking forward to getting more stats on the meteor (speed, angle, initial orbit?) if/when they're determined.

My initial estimates are:

entry speed: 13 km/s
inclination: 22.4°
radiant ra: 21:50 (327.7°)
radiant dec: -37.5°

Looks like a typical asteroid belt object.  It was visible for at least 10 seconds.  Major airburst at about 35 km altitude.  The videos don't seem to hint of a major fragment surviving that blast.  Without careful analysis of the videos and wind data maybe some fragments reaching the skerries off the Koster Islands can't be ruled out, but the probability seems very low.

The (cloudy) sky above Oslo also got illuminated, but I didn't see it myself, I only see it on the video, but not so impressive as further south.

I got tons of e-mails and phonecalls from witnesses, and for those who got a clear view of the entire track it was likely a once-in-a-lifetime experience.
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30 Nov 2020 06:48

midtskogen wrote:
Watsisname wrote:
Source of the post  Looking forward to getting more stats on the meteor (speed, angle, initial orbit?) if/when they're determined.

My initial estimates are:

entry speed: 13 km/s
inclination: 22.4°
radiant ra: 21:50 (327.7°)
radiant dec: -37.5°

Looks like a typical asteroid belt object.  It was visible for at least 10 seconds.  Major airburst at about 35 km altitude.  The videos don't seem to hint of a major fragment surviving that blast.  Without careful analysis of the videos and wind data maybe some fragments reaching the skerries off the Koster Islands can't be ruled out, but the probability seems very low.

The (cloudy) sky above Oslo also got illuminated, but I didn't see it myself, I only see it on the video, but not so impressive as further south.

I got tons of e-mails and phonecalls from witnesses, and for those who got a clear view of the entire track it was likely a once-in-a-lifetime experience.

Statistically how common do you think something like this is?  It's a bolide for sure and I looked up records for them and the brightest ones ever seen were around -20 so yours was right up there in that range.
 
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30 Nov 2020 07:56

A-L-E-X wrote:
Source of the post Statistically how common do you think something like this is?

Certainly weekly somewhere in the world.  Two such events in the same geographical area (southern Sweden) within 3 weeks, however, are rare.  Such events are usually years apart.

There was another event in Japan just one hour before the one in Sweden.
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