Sciency Words: Coatlicue

June 8, 2018

Today’s post is part of a special series here on Planet Pailly called Sciency Words.  Each week, we take a closer look at an interesting science or science-related term to help us expand our scientific vocabularies together. Today’s term is:

COATLICUE

You may recall the famous words of Carl Sagan: “We’re made of star stuff.”  Turns out we’re not made of just any old star stuff.  No, a great deal of our stuff came from one star in particular, a giant star named Coatlicue that went supernova about 4.5 billion years ago.

I first saw this name in a recent article from Scientific American called “The New Biography of the Sun,” which in turn referenced a paper from the journal Astronomy & Astrophysics titled “Solar System Genealogy Revealed by Extinct Short-Lived Radionuclides in Meteorites.”

In short, certain radioactive isotopes found in our Solar System can be thought of as our Solar System’s D.N.A.  The authors of that “Solar System Geneaology” paper used some of those isotopes (most notably aluminum-26) to try to reconstruct our Sun’s family tree and give us some idea about what the Sun’s “mother” must have been like.

Coatlicue would have been a giant star, approximately 30 times as massive as our Sun, ensconced within a giant molecular cloud along with other giant star siblings.  This is sort of like what we see today with the stars of the Trapezium inside the Orion Nebula.

About 4.5 billion years ago, Coatlicue went supernova.  The explosion accomplished two things: it seeded the surrounding molecular clouds with heavy elements (like aluminum-26) and, because of the force of the explosion, caused those molecular clouds to compress, triggering new star formation.

I have to confess that I feel like there’s a lot of guesswork and speculation going on here about how, specifically, Coatlicue died and how, specifically, the Sun and its planets were born.  But the general idea that the death of one star triggers the formation of others is consistent with what we already know about star formation, so it makes sense to me that something like this must have happened for our own Solar System.

As for the name Coatlicue (which I believe is pronounced Kwat-LEE-kway), that comes from Aztec mythology.  Coatlicue was the mother of the Sun.  So that makes sense.  In the myth, Coatlicue was also the mother of the stars, which actually sort of matches up with the science too.  That supernova explosion 4.5 billion years ago would have triggered the formation of other stars—perhaps several hundred of them—in addition to our own Sun.

I didn’t see this in either Scientific American or that “Solar System Genealogy” paper, but I’d like to believe Coatlicue might not have been totally destroyed in that supernova.  Perhaps some remnant is still out there, living on as a neutron star or a black hole or something.  If so, I doubt we’ll ever find it, but if I know anything about mothers, I’m sure our Sun still hears from Coatlicue every now and then.


Sciency Words: Baily’s Beads

February 16, 2018

Today’s post is part of a special series here on Planet Pailly called Sciency Words. Each week, we take a closer look at an interesting science or science-related term to help us expand our scientific vocabularies together. Today’s term is:

BAILY’S BEADS

This is going to be a quick one. I sort of blew all my writing hours this week finishing the first episode of my new short story series: Omni-Science. I don’t regret that. Writing Omni-Science felt awesome, and I hope you liked reading it.

The writing prompt that inspired Omni-Science was this photograph of the “Mondretti cylinder.”

That’s a very strange and mysterious image, certainly strange and mysterious enough to get the machinery in this writer’s brain started. But being the science nerd that I am, I also recognized that this is actually a time-lapse/composite image of a solar eclipse, showing off the “Baily’s beads” effect. (Also when I downloaded the image, the file name had the words “Baily’s beads” in it, which removed any doubts I had about what I was really looking at.)

As I’m sure you know, the Moon is not a smooth, perfect sphere. It’s covered in craggy terrain, and so during an eclipse, just before the Sun disappears entirely behind the Moon, the last rays of sunlight peak out from the gaps between mountains and craters and so forth. As a result, those of us who are using proper safety gear get to see these “beads” of light around the edges of the Moon.

I’m guessing Francis Baily was not the first person to notice this, but in 1836 he became the first to explain it in a paper for the Royal Astronomical Society titled “On the remarkable phenomenon that occurs in total and annular eclipses of the sun.” Those 19th Century English astronomers certainly did have a way with words, didn’t they?


Sciency Words: Spectroscopy

September 2, 2017

Welcome to a special Saturday edition of Sciency Words, because sometimes life gets in the way of regular blogging schedules. Each week (normally on Fridays) we take a closer look at some science or science-related term so we can all expand our scientific vocabularies together! Today’s term is:

SPECTROSCOPY

What color is it? It sounds almost like a childish question, but as we look out into space, trying to study the Sun and other stars and distant planets, we can learn a great deal just by figuring out what color things are.

The science of spectroscopy has a long history, beginning with Isaac Newton. In the late 1600’s, Newton demonstrated that pure white light can be split apart into a rainbow of color using a prism. Newton called this a spectrum, from the Latin verb specto, meaning “I observe” or “I see.” (According to my trusty Latin-English dictionary, the noun spectrum also meant “apparition” or “ghost.”)

Over the decades and centuries to come (click here for a detailed timeline), scientists used increasingly sophisticated combinations of lenses, mirrors, and prisms to study Newton’s spectrum in greater detail. They also experimented on a wide variety of light sources: sunlight, starlight, firelight, and even electrical sparks.

An especially noteworthy experiment in 1752 showed that burning a mixture of alcohol and sea salt produced an unusually bright yellow band in the middle of the spectrum (we now know this to be a emission line for sodium). And in 1802, another experiment on sunlight revealed multiple dark bands in the Sun’s spectrum (which we now know are absorption lines for hydrogen, helium, and other elements in the Sun’s photosphere and corona).

All the colors of the rainbow, except a few are missing. This is an absorption spectrum.

It wouldn’t be until the early 20th Century, with the development of quantum theory and, specifically, Niels Bohr’s model of the atom, that anyone could explain what caused all these spectral lines.

No rainbow, just a few specific colors. This is an emission spectrum.

In Bohr’s atom, the electrons orbiting an atomic nucleus can only occupy very specific energy levels. When electrons jump from one energy level to another (the true meaning of a quantum leap), they either emit or absorb very specific frequencies of light. The light frequencies are so specific that they act as a sort of atomic fingerprint.

And so today, as we look out into the universe, seeing the glow of stars and the absorption patterns of planetary atmospheres, it’s possible for us to identify the specific chemical elements we’re seeing, even across the vast distances of space, simply by asking what color is it?


One Last Thing About the Eclipse

August 30, 2017

This hasn’t been much of a research week for me. I’m more focused on the fiction side of my writing at the moment, rather than the science stuff.

So today I’m just sharing some artwork, something I didn’t quite get done in time for the eclipse.

You know, we are kind of lucky that we have these total solar eclipses. By some amazing coincidence, our large Sun and small Moon appear to be the same size in Earth’s sky, allowing the Moon to perfectly cover up the Sun.

That doesn’t happen anywhere else in the Solar System. That perfect planet-moon-star alignment is likely rare, perhaps even unique in our galaxy. So whenever we make first contact with aliens, and they start bragging about their luminous forests or crystal waterfalls or whatever, we Earthlings will have a unique and beautiful thing to brag about to: we have total solar eclipses.


Eclipse Day 2017 and Hermione Granger

August 23, 2017

One of my favorite fictional characters—one of the characters I most strongly identify with—is Hermione Granger from the Harry Potter series. She’s depicted as extremely bookish, and at one point we’re told she’s nervous about flying because it’s “something you couldn’t learn by heart out of a book.”

Yup, that sounds like me. I’ve spent an enormous amount of time studying science, but almost everything I know comes out of books rather than from hands on experience.

And so as the Great American Eclipse of 2017 approached, I felt increasingly nervous, just like Hermione going out for her first flying lesson. I’d read a lot about the eclipse, done pretty thorough research about the kinds of glasses I’d need to buy, and yet… I still felt horribly unprepared.

To make matters worse, the eclipse glasses I’d ordered online seem to have gotten lost in the mail. On the day of the eclipse, they still hadn’t arrived. I had a backup plan, but I wasn’t sure if it was going to work. I’d read online that you can use a pair of binoculars to project an image of the Sun onto a piece of paper. Again, I’d read about this, but I’d never tried to do it, and I wasn’t 100% convinced this was going to work for me. Some of the instructions I’d read sounded kind of complicated.

And yet to me extraordinary delight, it worked! My hands were a bit shaky, but I was able to project the Sun onto a page of my sketchbook and watch as the Moon slowly moved across the image.

My hastily improvised eclipse observatory.

Watching the eclipse turned out to be a highly emotional experience for me. I’ve been going through some things in my personal life, and this was a powerful reminder that no matter what happens, the universe keeps turning. Also, I realized at one point that the binoculars I was using originally belonged to my Dad, so in a sense it was like I got to share the experience with him.

And lastly, for a Hermione Granger-type person like me, this was one of those rare moments when something I read about became real to me. Maybe it wasn’t as exhilarating as learning to fly on a broomstick, but still… Eclipse Day 2017 was a magical experience for me.


Sciency Words: Coronal Heating Problem

June 9, 2017

Today’s post is part of a special series here on Planet Pailly called Sciency Words. Each week, we take a closer look at an interesting science or science-related term to help us expand our scientific vocabularies together. Today’s term is:

CORONAL HEATING PROBLEM

This is the Sun. He’s kind of a big deal, and he knows it.

The interior of the Sun is several million degrees Celsius. By comparison, the surface of the Sun is quite chilly. It’s only a few thousand degrees. Still, if you were standing on the surface of the Sun, you wouldn’t last long.

But before you launch yourself into space to escape the heat, there’s something you should know: as you fly away from the Sun, passing through the corona, the temperature starts getting hotter again. It’s not quite as hot as the interior, but still… we’re back into million-plus degree heat.

If that doesn’t make sense to you, that’s okay. It doesn’t make sense to me either, or anyone else. Astro-scientists have been baffled by this for decades now. They call it the coronal heating problem.

I first heard about the coronal heating problem back in 2014, when I was starting my research for what became the 2015 Mission to the Solar System. To be honest, it’s not something I’ve spent a lot of time thinking about since then. Every once in a while, it comes up again and I think, “Oh right… so they still haven’t figured that out yet?”

But as you may heave heard last week, NASA’s on the case. Their newly named Parker Solar Probe is going to skim very close to the Sun and try to figure out what the heck’s going on.

Parker is scheduled for a launch window in July/August of 2018. Its mission is expected to last until 2025. So hopefully a decade from now, whenever I’m reminded of the coronal heating problem, it won’t be a problem anymore, and I’ll be able to think, “Oh right… they finally figured that out!”


Sciency Words: Frost Line

December 23, 2016

Welcome to a very special holiday edition of Sciency Words! Today’s science or science-related term is:

FROST LINE

When a new star is forming, it’s typically surrounded by a swirling cloud of dust and gas called an accretion disk. Heat radiating from the baby star plus heat trapped in the disk itself vaporizes water and other volatile chemicals, which are then swept off into space by the solar wind.

But as you move farther away from the star, the temperature of the accretion disk tends to drop. Eventually, you reach a point where it’s cold enough for water to remain in its solid ice form. This is known as the frost line (or snow line, or ice line, or frost boundary).

Of course not all volatiles freeze or vaporize at the same temperature. When necessary, science writers will specify which frost line (or lines) they’re talking about. For example, a distinction might be made between the water frost line versus the nitrogen frost line versus the methane frost line, etc. But in general, if you see the term frost line by itself without any specifiers, I think you can safely assume it’s the water frost line.

Even though our Sun’s accretion disk is long gone, the frost line still loosely marks the boundary between the warmth of the inner Solar System and the coldness of the outer Solar System. The line is smack-dab in the middle of the asteroid belt, and it’s been observed that main belt asteroids tend to be rockier or icier depending on which side of the line they’re on.

It was easier for giant planets like Jupiter and Saturn to form beyond the frost line, since they had so much more solid matter to work with. And icy objects like Europa, Titan, and Pluto—places so cold that water is basically a kind of rock—only exist as they do because they formed beyond the frost line. This has led to the old saying:

dc23-outer-solar-system-christmas-party

Okay, maybe that’s not an old saying, but I really wanted this to be a holiday-themed post.