BAN #212: Yellow birds, California time-lapse, Earth’s not-quite-iron outer core

About this newsletter

Ooo, meta

Hey, it’s issue 212, the same number of Fahrenheit degrees in boiling water! COINCIDENCE? Well, yeah, but still as good a time as any to quickly plead with y’all: If you know folks who would enjoy hearing more from me in a newsletter, then please ask them to subscribe! I do what I can to relentlessly hawk this thing, so if you help, well, it helps. J

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Red in Tooth and Claw

I live in rural Colorado, and we get nature here

One sure sign of spring finally returning to Colorado — besides temperature fluctuations from liquid nitrogen to boiling lead — is the orderly and sequential return of birds. Robins and meadowlarks are back, and then killdeer (and YIKES are they loud), and now I’m seeing pelicans and heron, too.

One bird I didn’t even know existed until last year is the yellow-headed blackbird, which is a pretty striking fella. I saw a bunch last year, and thought, “What are THOSE?” so I decided to search online; describing them in the search engine I typed “yellow headed blackbird” and got back pretty much the results you’d expect.

They came and went over just a few days last year, and my wife and I have been wondering if they’d be back. Then earlier this week this one popped up in a tree we now just call “the bird tree”:

Wow! And yeah, hence the name.

There were four in total in the tree, and I could only get two in the frame at once with any detail:

I haven’t seen any since. Hopefully more will show up; they like the seeds in our feeder and they are just amazing to watch.

I mean, hey, if I have to be stuck at home, at least there’s a show going on outside.

Pic o’ the Letter

A cool or lovely or mind-bending astronomical image/video with a short description so you can grok it

Michael Shainblum is an inarguable maestro of time-lapse photography. I’ve posted about him many, many times, and every new release of his is cause to take a few minutes, sit back, relax, make the video full screen, and be overwhelmed by beauty.

His newest, “The Golden State”, is no exception. I lived in California for seven years, and its beauty is palpable, but made ever more so through Shainblum’s lens.

Enjoy. And a reminder: Air is a fluid.

A Bit o’ Science

The entirety of science is too much for one sitting. Here’s a morsel for you.

Unlike the sky, the Earth is opaque, making it difficult to see much more than a nanometer or two into it. But geologists have a few ways of figuring out what’s beneath our feet. One is if stuff down there comes up here, through volcanism or orogeny.

Yes, that word is fun because it sounds a bit dirty. But look it up.

Another is when there are earthquakes, which send waves through the Earth. As they pass through the interior they change, and this can be measured using seismometers. It’s how we know the Earth’s outer core is liquid, in fact (oooo, foreshadowing).

A third is in the lab. When materials are compressed using incredible pressure they behave differently, and this can be used to figure out what sorts of minerals and such lay deep inside our planet.

It’s this third one that just resulted in an interesting finding: The Earth’s liquid iron outer core is not as dense as liquid iron should be at that pressure and temperature.

Scientists used a diamond anvil to generate huge pressure on a sample of hot, liquid iron, and then used sophisticated techniques (that took two decades to get right) to measure its characteristics. At a temperature of just over 4000°C, and a pressure of 116 billion Pascals (well over a million times atmospheric pressure at sea level, yikes), they found the sample had a density of about 10 grams per cubic centimeter.

But calculations of the density of the outer core show it to be 8% less dense than this. Why?

Most likely, it’s not pure iron. If there are minerals or other impurities floating around in there, they would reduce the density somewhat. The question, obviously, is what are they? The answer is: No one knows, yet.

If this seems academic, it ain’t. The Earth’s magnetic field is generated in the outer core. As hot ionized iron circulates around it creates conditions that make our geomagnetic field. We still don’t understand how that works, really. Every 100,000 to one million years or so the magnetic field reverses polarity (north becomes south and vice versa) and no one really know why. The last one was 800,000 years ago, and new results show it took over 20,000 years to settle down.

The magnetic field protects us from the solar wind and huge solar storms, so understanding this better is A Good Idea™. Our satellites and power grid depend on it, and can be damaged if things go awry.

It can be easy to dismiss some experiments in science because they sound foolish. “We need a million bucks to heat up iron and squeeze it really hard with a diamond” may not get you a grant, but “We need to understand the Earth’s core better because the survival of our technological civilization depends on it” might grease the wheels a little more.

And even better: It’s true.

Et alia

You can email me at [email protected] (though replies can take a while), and all my social media outlets are gathered together at about.me. Also, if you don’t already, please subscribe to this newsletter! And feel free to tell a friend or nine, too. Thanks!