Mommy, what are planets made from?

I’ve wanted a piece of Tagish Lake ever since I first heard about the event.  It’s the first meteor fall that I heard about as it happened and immediately thought “I wish I could have a piece of it.”  Little did I know, Tagish Lake would turn out to be a very special meteorite, and that eventually, I really could have a piece of it.  It’s one of the few meteorites who’s original orbit could be accurately determined from it’s entry path, since it was observed by so many people, radars, etc.  NORAD kinda keeps an eye on shit streaking in from space over North America.

Before it hit the atmosphere, it weighed in at 50-100 tons.  It exploded in the upper atmosphere, with a force of about 1/10th of a Hiroshima, the standard unit of measure for ridiculously large explosions.   Luckily, some of the fragments that didn’t get obliterated rained down on a frozen lake.  They were recovered just as the weather was starting to warm up.  In a few weeks, the ice was melted.  If they’d been a little later, they’d have found nothing.  As is, only about 10kg was recovered on the ground in total, much of it in the form of little piles of powder and crumbles.  It has a texture very similar to charcoal.

A Fragment of the Tagish Lake Meteorite

A Fragment of the Tagish Lake Meteorite

It’s part of a class known as carbonaceous chondrites, meaning it’s got a fuckload of carbon in it, thus the pitch black coloring, and chondritic, meaning that it’s undifferentiated, i.e. came from a time before planets began to stratify, which means it predates the formation of the planets themselves.  Put another way, its part of what would have made a planet, if Jupiter hadn’t rolled into the neighborhood all drunk and rowdy.  These are some of the oldest things in our solar system.  They are older than the Earth itself.  It’s about 4.5 billion years old.  Our Sun is about 4.7 billion years old.

Early on, Earth was much too hot to hold onto any water.  Fortunately, there was an ample supply was held in reserve, out there in the asteroid belt, where it was a little cooler.  As Jupiter migrated inwards towards the Sun, it cleared out the competition on the way in, swallowing some, ejecting others from the solar system, but most importantly, sending a metric fuckton of them towards the Sun, and the lowly inner planets. In a gravitational battle between Jupiter and a small moon, Jupiter wins.  You didn’t see Dick Cheney blow up the princesses gas giant homeworld, did you?  No, because Jupiter woulda donkeypunched him straight to DVD.  This period is known as the Late Heavy Bombardment.  It would have been a pretty unpleasant time to be on Earth.  It’s when the maria, and all the big craters you see on the moon were formed, as piles, and piles of asteroids large and small(some of them very large), collided with the Earth and Moon.  Anyway, it’s a good thing, because without those, there wouldn’t be any water here, or much carbon.  You know, the stuff pretty much everything you know and love is made with.   Say “Thank you, Jupiter…”

Destabilized onto my shelf, yo.

Destabilized onto my shelf, yo.

Tagish Lake is more special than just that, though.  We know exactly(probably) where it came from, specifically, an asteroid named Irmintraud 773.  By measuring Irmintraud 773’s light with a spectrograph, and comparing its spectra to the spectra of Tagish Lake, measured here on Earth, we can see that the two are a very close match.  It’s a slightly closer match to a different asteroid, Hadea 368, but Irmintraud773 orbits pretty close to a Kirkwood Gap,where orbits get destabilized due to gravitational interactions with Jupiter.  This tends to kick stuff towards the inner part of the solar system, where they occasionally collide with Earth, because shit rolls downhill.

But wait!  It’s more special than that!(Oh god, I Jobsed.)  It’s chock full of things like diamonds, fullerenes, and all kinds of organics, including a few amino acids, the things proteins are built from.  According to recent news, it has 4 times more formic acid than any other known meteorite.   Take that, all other meteorites!  Formic acid is useful in facilitating chemical reactions between organic molecules.  That probably has something to do with why ants use it in their venom.

The diamonds inside are really tiny, micrometers or nanometers across, but Tagish Lake contains more of them than any other known meteorite.  It also contains fullerenes, cage-like molecules of carbon that can trap other atoms, or even small molecules inside.  The fullerenes and diamonds are the product of ancient supernovas in solar systems that predated our own, making them potentially much older than 4.5 billion years.  Inside those fullerenes are gasses trapped during their creation billions of years ago in the aftermath of a dying star, before our star was even born.

It looks exactly like charcoal.  In a sense, that’s exactly what it is.


From marbles to meteorites

Ok, so, meteorites. I’m gonna do a post with multiple items this time, because I’m trying to make a kickass point. In general, there are several different general types of meteorite. They are either stony (chondrites), iron (iron), a mix of iron and rock(stony/iron, including pallasites), or a funky 4th category(carbonaceous chondrites) that are crazy carbon rich. I’ve got a few meteorites, but not all the ones I want. I’m gonna include some pictures from things I don’t have yet, just to demonstrate my overall point, and to show why I must own them.

Now as we all know, the Earth’s interior is differentiated into different layers, with different properties. We have the rocky outer crust, where we live, which is ridiculously thin, between 2 and 30 miles thick or so. Considering the Earth is about 8000 miles in diameter, that’s pretty damned thin. Next, we have the still rocky, but now fluid mantle. Here the pressure and temperature has melted the rock and turned it into a sort of super-sticky fluid. The mantle can be further subdivided into an upper/lower, but that’s not really relevant, so I’ll just say the mantle is about 1800 miles thick. Beneath that we have the outer and the inner core, both consisting primarily of iron and nickel. Almost everyone knows about the iron, but most people don’t know there’s quite a bit of nickel too. Why, you might ask?

Well, back in the olden days, before the Earth, or the Sun existed, a really big star blew up somewhere pretty near to the cloud of gas that was eventually to be our solar system. This star blew up because it had started fusing iron in it’s core, and for stars, this is the end of the road. Fusing iron doesn’t produce energy, it consumes it. It starts sucking energy out of everything around it, and the outward radiation pressure drops. Gravity starts to win. But the star does not go quietly. As it simultaneously implodes, and explodes, its core becomes a black hole, while the rest of its innards, get ejected at a significant fraction of the speed of light in the kind of explosion that’s visible across the Universe. In the process, pretty much every chemical element from iron on up in the periodic table is created, all within a few seconds. That’s where uranium is made. That’s where gold is made.

Eventually the shockwave, followed later by the ejected bits collide with a gas cloud, and cause a part of it to collapse, just like blowing into a cloud of smoke. Now, the important thing, is that these supernova explosions are very rich in a particular isotope of iron called Iron-60. Iron-60 is radioactive, and it decays into…Nickel-60! This is where all that nickel came from. So, when you’re looking at an iron meteorite, you’re looking at the pieces of a dead star. The ratio of iron to nickel tells you something about the neighbors during the period when it formed. It tells you something about the stars that gave birth to it. When that meteorite formed, it was probably mostly iron. Over time, the radioactive Iron-60 in it decayed and turned into very stable Nickel-60, where it has remained ever since.

So, then some shit happened, a star formed, and along with it, a bunch of planets. Some of those planets are still with us today. Others, well…they didn’t make it. Our solar system was one crazy place back then, with a whole lotta shit flying around in a whole lotta directions, colliding, accreting, etc. Point is, planets are being assembled. Violently. Sometimes they get disassembled by accident. And that’s how meteoroids are born!

Korra Korrabes meteorite from Namibia

This is a stony meteorite, technically known as a chondrite. There are many different varieties of these, just like there are many different varieties of rock on Earth. This particular one is an “H3 Chondrite” named Korra Korrabes (after where it was found). It’s a breccia, which basically means it’s composed of loose gravel filled with finer dirt, and then compacted. It’s a bit like a natural concrete, I guess. This one came to earth in Namibia, and was later discovered in 1996 in a dry river bed by a farmer. It is a piece of the crust/mantle of a planet that’s no longer with us.

A piece of the Sikhote-Alin fall

A piece of the Sikhote-Alin fall

This is an iron/nickel meteorite. It’s from Sikhote-Alin, which is a mountain range in Siberia. It’s technically classified as “coarsest octahedrite”, which refers to the crystalline structure of the metal it’s composed of. The dimples in the surface are called regmaglypts, and they’re basically the result of air pressure on the molten outer surface of the meteorite after it meets the atmosphere and heats up. It’s a lot like what would happen if you pursed your lips and blew really hard into a bowl of ice cream. If you cut it open(the meteorite, not the ice cream,) it would look something like this.

Toluca-IAB iron meteorite w/widmanstatten pattern

Toluca-IAB iron meteorite w/widmanstatten pattern

It’s called a “Widmanstatten Pattern” and it is unique to iron/nickel meteorites. It can only be created when a molten chunk of iron/nickel floating in zero gravity under a near perfect vacuum, is allowed to cool veeeerrrry slowly over millions of years, giving these amazing crystals time to form. The bands basically represent different nickel/iron alloys. Because the ratio of iron:nickel is different between the stripes, the crystal structures they form are slightly different. This manifests itself as a series of criss-crossing lines throughout the body of the meteorite. This particular one is from the Toluca, Mexico meteorite. When it was found, in 1776, the locals were turning chunks of it into farm equipment, cuz, hey, free iron! Its constituent atoms were born in an ancient star that went supernova. It got its shit together, and became the core of a planet that’s no longer with us. It died in its youth, victim of a driveby planet. RIP, little meteor. RIP.

Imilac Pallasite

Imilac Pallasite

This is a pallasite. These things are fucking beautiful, and I MUST own one. It’s strange, it’s got a whole crapload of iron, but it’s not pure iron/nickel like the other ones. Why? Well, I’ll tell you. That’s the boundary between the mantle, and the core of a planet that’s no longer with us. Why is it all gemstoney? Well, that’s how gemstones are made. Immense heat + immense pressure + a stocking full of coal = diamonds. In this case, it’s Olivine, also known as Peridot. Are you born in August? How’s that for a birthstone to make your friends jealous?

Each of these things is older than any rock, anywhere on Earth. They’re all about 4.5 billion years old, a bit older than the Earth itself. They’re the shattered remains of planets that just didn’t quite make it. They survived long enough to differentiate into an iron core, with a rocky outer crust, and that incredible boundary layer. They just couldn’t quite hang in there for the long haul though. Those early few hundred million years were pretty hazardous. Imagine how hazardous it has to be for an object the size of a planet to be routinely obliterated? It’s like that.

Flash back to Starwars, Vader is destroying himself some homeworlds just to make the princess cry, cuz he’s hard like that. Remember that planet exploding? This is like that. Only for real. And on a massive scale, like “OH FUCK, LOOK OUT! HERE COMES A PLANET!” If you find yourself in such a situation, it’s probably best that you grab your ankles, and think of England.

When you look up at the moon, and you see these giant scars, those were some pretty massive bodies smashing into it at pretty incredible velocities. It was such an impact that created our moon in the first place, when one of those mars-sized erstwhile planet wannabes picked a fight with the erstwhile planet wannabe Earth, and lost. The impact was sorta oblique, so it happened to fling big chunks of both bodies into orbit around the new Earth + 1. Those chunky bits coalesced into our Moon.

Oh, the 4th category, Carbonaceous Chondrites? Those are basically comets. They formed in the outer solar system, around Pluto’s neighborhood. They’re chock full of water and carbon, just the kind of thing a growing planet needs to establish a biosphere. The Tagish Lake meteorite is an excellent example of a carbonaceous chondrite.

Ok, so anyway, my point. Science rules, Natural Selection doesn’t just apply to monkeys and Creationists, and meteorites aren’t just rocks from space. They tell you something about where you came from, and where they came from, where the Earth, and the Sun themselves came from. Every time I think about what these represent, it puts me into a state of awe that words just can’t convey. And yet, it’s just a rock, or just a lump of metal. Hell, I bet you could make some damned fine farm equipment out of it.

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