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.

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