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midtskogen
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19 Nov 2017 01:30

I caught a nice southern Taurid on camera last night.  It exploded reaching -14 magnitude or brighter.

tauride-20171119.jpg

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21 Nov 2017 13:09

The 16th November event was recorded by infrasound stations over a large part of the northern hemisphere, as far away as Alaska and Mongolia.  CTBTO published this map:
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But they're too far to the east.  The event actually happened near Lake Inari in Finland.
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22 Nov 2017 08:49

I've been quoted by CBS in this story

We know much more now, though.  The headline is my initial estimate, which I think still holds.  But the location has been much better pinpointed.
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22 Nov 2017 10:05

So, even if the area can hardly be inspected right now, searches will be postponed in a prolonged period of time, when temperatures will be more favorable If I'm interpreting right?
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22 Nov 2017 11:04

As the Finnish article says, the Finnish guys have already been to the area, but it's a difficult search.  It's a remote area, there are only a few hours of daylight/twilight a day, and I believe that there are restrictions on the use of snowmobiles in that area, so they have to ski.  I think it's a few hours on skis from the nearest road just to get into the fall zone.  Some meteorites may have dropped over Lake Inari, but it's a big lake and not safely frozen yet despite temperatures around -20°C recently.  A heavy snowfall is expected on Friday, which will not make searched very practical until spring.  The snow is usually gone by late May in this area.
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12 Dec 2017 11:34

Finally we have a camera in Northern Norway in our meteor network.  Online just in time for the Geminids.  And the northern lights give a nice touch. :)
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23 Nov 2020 19:32

It's been a long while, but I've saved up and recently added a few new meteorites to the collection. I'm very excited about these ones!

First is a piece of lunar meteorite NWA 11474.

► Show Spoiler


Yes, this is a rock from the Moon, with a fascinating history. It is a breccia, or a mixture of broken fragments that have been compactified into a new rock, like the lunar form of a terrestrial conglomerate. On the Moon, the constant bombardment of meteorites breaks up and throws rocks around, so any particular location on the Moon has a regolith made up of rock fragments of all different sizes that came from all over. Finally some mildly larger impact, perhaps creating a crater a few kilometers across, launched some of these rocks away from the Moon entirely and into an orbit around Earth, perhaps remaining in orbit for a few tens of thousands to millions of years, before landing on Earth. Most lunar meteorites are discovered in Antarctica, or in this case in northwest Africa (hence the NWA designation).

There are also a few ways to tell (besides a geochemical analysis) that this is a Moon rock and not some terrestrial rock. The fragments within terrestrial conglomerates tend to be rounded, if they were formed in rivers. They also tend to be of similar size and compositions. The fragments in a lunar breccia on the other hand are never round, and have a fractal distribution of sizes. If you zoom in on a part of one, it will look much the same.

Some more neat info and images of lunar meteorites, with comparisons to rocks in the Apollo sample, here.


Next is Martian meteorite NWA 11288. (Label says 407 grams, which was the whole meteorite, while this piece is 140mg.)

► Show Spoiler


Last, a slice of an iron meteorite, Muonionalusta, displaying the octahedral Widmanstätten pattern.

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24 Nov 2020 12:07

Neat, those are rare meteorites.  Lunar and Martian, I mean.  My entire meteorite collection consists of a small piece of Valle which was given to me by its finder.  A pretty common class of meteorite.

The search is still on in Sweden, but no reported finds yet.  Something punching into the troposphere at several km/s is a good sign of something big, as well as the sounds recorded in some videos.  I'm still hopeful, and eager to know what kind of object this is.
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A-L-E-X
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24 Nov 2020 14:53

are those tektites?!
 
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24 Nov 2020 15:16

A-L-E-X wrote:
Source of the post are those tektites?!

No, tektites are glass-like blobs of material that was melted and ejected by impacts occurring on Earth, so they are made mostly of Earthly materials. I have an impact generated glass (Libyan desert glass), which might be called an "impactite", but no tektites.

The above meteorites are all fairly unaltered rocks from the parent body that were ejected and made it to Earth. They came from the Moon, Mars, and the core of an asteroid, respectively.

midtskogen wrote:
Source of the post My entire meteorite collection consists of a small piece of Valle which was given to me by its finder.  A pretty common class of meteorite.

That's awesome. I love the story of the find for this one, and that you obtained it from the original finder! Imagine recreating in the mountains, and stumbling across something like that. That would be a very good day. :)
 
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24 Nov 2020 22:50

Watsisname wrote:
A-L-E-X wrote:
Source of the post are those tektites?!

No, tektites are glass-like blobs of material that was melted and ejected by impacts occurring on Earth, so they are made mostly of Earthly materials. I have an impact generated glass (Libyan desert glass), which might be called an "impactite", but no tektites.

The above meteorites are all fairly unaltered rocks from the parent body that were ejected and made it to Earth. They came from the Moon, Mars, and the core of an asteroid, respectively.

midtskogen wrote:
Source of the post My entire meteorite collection consists of a small piece of Valle which was given to me by its finder.  A pretty common class of meteorite.

That's awesome. I love the story of the find for this one, and that you obtained it from the original finder! Imagine recreating in the mountains, and stumbling across something like that. That would be a very good day. :)

Wat, is there a special term for meteorites that came from Mars or the Moon?  I remember a very famous one from Mars was discovered in Antarctica!

I just read about the "nonterrestrial" origin theory of tektites, which was rather popular in the 90s and I think that's why I associated tektites with meteorites from other planets.
 
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24 Nov 2020 22:58

A-L-E-X wrote:
Source of the post Wat, is there a special term for meteorites that came from Mars or the Moon?  I remember a very famous one from Mars was discovered in Antarctica!

Not really, just Martian meteorite and lunar meteorite. I've heard the latter as "lunaite" sometimes, which is cute but I think not often used.

Antarctica is a common hunting ground for meteorites of all types, not because more fall there, but because they are easier to find there, and they can be concentrated by the movement of glaciers. The desert in northwest Africa is also a popular hunting ground. Lunar and Martian meteorites have been found in both places. As far as I know, none have yet been found elsewhere. They surely exist on every continent, but they are very uncommon and difficult to find -- much more so than metallic meteorites.
 
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24 Nov 2020 23:42

How do these happen, Wat?  Is it basically a large meteorite hitting either the Moon or Mars and chipping off a piece, which happens to come hurtling towards the earth (aided by the fact that the gravity is quite low there.)  Wouldn't it be something if one day we found an earth rock on the Moon or Mars?
 
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25 Nov 2020 00:53

A-L-E-X wrote:
Source of the post Wouldn't it be something if one day we found an earth rock on the Moon or Mars?

More realistic and equally awesome: What if we found an Earth meteorite on Earth.  Ejected perhaps several hundred million years ago, isolated from all geological processes, then returning to Earth.  It could even be a meteorite with real fossils.  But for something to escape Earth the impact must be much larger than on the Moon and Mars, so I would expect such rocks to be highly metamorphed and not so much intact time capsules.
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25 Nov 2020 06:35

midtskogen wrote:
A-L-E-X wrote:
Source of the post Wouldn't it be something if one day we found an earth rock on the Moon or Mars?

More realistic and equally awesome: What if we found an Earth meteorite on Earth.  Ejected perhaps several hundred million years ago, isolated from all geological processes, then returning to Earth.  It could even be a meteorite with real fossils.  But for something to escape Earth the impact must be much larger than on the Moon and Mars, so I would expect such rocks to be highly metamorphed and not so much intact time capsules.

Wow, I wonder how large the impact would have to be for this to occur?

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