Sciency Words: Thiea

June 1, 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:

THEIA

When I wrote about the Nice model, I said it does a nice job (pun intended!) of explaining how the planets of the Outer Solar System started out, and how they ended up where they are today.  But what about the Inner Solar System?  Well, it turns out we may have started with a few more planets than we have today, and one of those hypothetical early planets has been named Theia.

Technically speaking, Theia wouldn’t have been a planet (not according to the I.A.U. definition), but it was definitely planet-sized, perhaps as large as modern day Mars.  But Theia had to share its orbit with another planet that wasn’t technically a planet (yet): Earth.

Theia got stuck near one of Earth’s Lagrange points, about 60 degrees ahead of Earth in Earth’s almost circular orbital path.  There’s some weird gravitational voodoo going on at these Lagrange points, and so this arrangement of Earth and Theia could theortically have remained stable long term.

Except Jupiter and/or Venus disrupted the gravitational balance, pulling Theia a little this way, a little that way, nudging Theia away Earth’s Lagrange point and closer to Earth itself, until one day….

I would call this the worst disaster in Earth’s history, except this collision was sort of the moment when Earth (as we know it) really began.  I gather there’s still a lot of disagreement about the details, like whether this was a head-on collision or more of a glancing blow, but the two really important things to know are:

  • Theia knocked a large amount of Earth debris into space. That debris eventually coalesced to form our Moon.
  • Most of Theia is probably still here.Theia has become part of Earth, and the bulk of Theia may have would up becoming Earth’s core.

This idea that early Earth suffered a cataclysmic collision with another planetary body has been credited to a lot of different people, but it first appeared in the scientific literature in this paper from 1975.  The name Theia wasn’t introduced until much later, in this paper from 2000.

In Greek mythology, Theia was the Titaness who gave birth to the Moon.  That checks out. The name definitely seems appropriate.  In the myth, Theia also gave birth to the Sun.  That part doesn’t match up with the science so well.

But not to worry!  In next week’s episode of Sciency Words, we’ll meet the Sun’s real mother.


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: Moon Village

February 9, 2018

In this week’s episode of Sciency Words, the Moon would like to ask a question, the same question it’s been asking since 1972:

The answer is we humans may be returning to the Moon fairly soon, perhaps within the next decade, but this time we’ll be bringing a far more diverse set of flags to add to the Moon’s collection.

The European Space Agency, also known as the E.S.A., is taking the lead on the next round of Moon missions. For the last few years, Johann-Dietrich “Jan” Wörner, the current E.S.A. director-general, has been talking up the idea of building a Moon village near the Moon’s south pole, a region where large quantities of water ice have been detected.

Apparently interest in Wörner’s Moon village has been growing steadily to the point that Wörner has been quoted saying the village is already “more or less a fact.” I have a feeling the recent successful test of SpaceX’s Falcon Heavy rocket will accelerate that growth in interest.

But my biggest question about this, and the reason I felt this was worthy of a Sciency Words post, is this: why aren’t we talking about a Moon base? Why is it a village? Apparently the terminology was a very deliberate choice. On the E.S.A. website, Wörner writes:

By ‘Moon Village’ we do not mean a development planned around houses, some shops and a community centre. Rather, the term ‘village’ in this context refers this: a community created when groups join forces without first sorting out every detail, instead simply coming together with a view to sharing interests and capabilities.

I remember in first or second grade painting a mural as a class project. Each student was free to paint whatever he or she liked within the guidelines set by the teacher. The Moon village sounds like a similar concept to me, with every participating country or company or other privately funded group doing their own thing within the broader guidelines set by the E.S.A.

I just hope the end result is not quite the eyesore that that mural was when I was a kid.


Sciency Words: Triangular Trade

January 26, 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 I’m really stretching my conception of science-related terms so we can talk about:

TRIANGULAR TRADE

When I was a kid, I had an extensive collection of cards from Star Wars: The Customizable Card Game. At one point, I was trying to trade with a friend to get his Millennium Falcon card, but I didn’t have anything my friend wanted. So we got a third person involved and set up a three-way trade. My extra Princess Leia card went to this third person, who then gave a rare star destroyer to my friend, who then gave me the Millennium Falcon I needed to complete my rebel fleet.

This was sort of like what happens in triangular trade. Like nerdy kids trading Star Wars cards (or non-nerdy kids trading, I don’t know, baseball cards or something), cities or regions or countries set up three-way trade arrangements for their exports. This kind of arrangement served as the basis for much of the world economy in the 18th and 19th Centuries, during the Age of Colonialism.

The most commonly cited example (unfortunately) is the slave trade, where the trade routes between Europe, Africa, and the Americas actually traced out a big triangle across the Atlantic Ocean. European nations exported manufactured goods to their African colonies, which then exported slaves to the American colonies, which then exported things like sugar, cotton, tobacco, etc to Europe.

Obviously triangular trade is more of a historical term than a sciency thing, but much like the word thalassocracy, I feel like this old, history-related term might become applicable again in a far-out, Sci-Fi future where humanity is spreading across the Solar System. And the reason I think that is because Robert Zubrin, one of the foremost Mars colonization advocates in the U.S., wrote about triangular trade in his book The Case for Mars and also in this paper titled “The Economic Viability of Mars Colonization.”

To quote Zubrin from his “Economic Viability” paper:

There will be a “triangle trade,” with Earth supplying high technology manufactured goods to Mars, Mars supplying low technology manufactured goods and food staples to the asteroid belt and possibly the Moon as well, and the asteroids and the Moon sending metals and possibly helium-3 to Earth.

So everybody wins! The people of Earth win, the colonists on Mars win, and all the prospectors and mine workers in the asteroid belt win! Even our moonbase wins (this part might seem counterintuitive, but the delta-v to reach Earth’s Moon from Mars is actually lower than the delta-v to reach the Moon from Earth). And this time, slavery isn’t involved!

Unless the high technology being exported from Earth includes robot slaves who then… hold on, I have to go write down some story ideas.


Sciency Words: Graben

December 15, 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:

GRABEN

According to the appendix of Frank Herbert’s Dune, a graben is defined as “a long geological ditch formed when the ground sinks because of movements in the underlying crustal layers.”

According to real life, a graben is… well, it’s exactly what Frank Herbert said it is. The term comes from a German word meaning trench, which is a nice, direct way to describe what grabens look like: trenches.

Grabens tend to form between two “normal faults” if the faults run more-or-less parallel to each other. In other words, they form when two masses of the planet’s crust start moving away from each other, allowing a thin sliver of material to sink down into the gap between them.

Fault-Horst-Graben.svg

Image courtesy: Wikipedia.

I used to think grabens could only form due to the movements of tectonic plates, which would mean we should only expect to find them on Earth—the only planet known to have active plate tectonics. But really grabens can occur on any world where the planetary crust is moving around, being pushed or pulled in different directions, causing the surface to stretch and crack.

That could explain why grabens, or at least surface features that look an awful lot like grabens, have been observed on the Moon, Mars, and other places in the Solar System. And perhaps that’s also why they were found (will be found?) on the planet Arrakis, all the way out in the Canopus Star System, according to Frank Herbert.


Sciency Words: Moon

September 29, 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:

MOON

There are three things I want to cover with today’s post. Firstly, for anyone who may not already know, Earth’s moon is officially called the Moon (with a capital M). Unless you don’t speak English, in which case it’s called whatever it’s called in your language, provided that you treat the word as a proper noun. This according to the International Astronomy Union (I.A.U.), the one and only organization with the authority to name and classify astronomical objects.

Phases of the Moon.

Of course the Moon is not the only moon out there, so I also want to talk a little about the official I.A.U. sanctioned definition of the word moon. Unfortunately there isn’t one, which seems odd given how the I.A.U. are such stickers about their official definition of the word planet.

A common unofficial definition is that a moon is any naturally occurring object orbiting a planet, dwarf planet, or other kind of minor planet (such as an asteroid or comet). Except this definition creates some problems:

Saturn has like a bazillion moons!

Since there’s no lower limit on size or mass, you could consider each and every fleck of ice in Saturn’s rings to be a moon.

The Moon isn’t a moon!

In a very technical sense, the Moon does not orbit the Earth. The Earth and Moon both orbit their combined center of mass, a point called a barycenter. In the case of the Earth-Moon system, the barycenter happens to lie deep inside the Earth, so this distinction may not seem important, but…

Pluto is Charon’s moon, and Charon is Pluto’s!

The barycenter of the Pluto-Charon system is a point in empty space between the two objects. Pluto is the larger of the pair, so we generally consider Charon to be Pluto’s moon; however, you could argue that Pluto and Charon are moons of each other. You could even write a love song about their relationship.

Of course I’m not seriously arguing that Saturn has billions upon billions of moons, nor am I arguing that our own Moon is not really a moon. There does seem to be some ambiguity about Charon’s status (is Charon a moon, or are Pluto and Charon binary dwarf planets?), but I’m not sure if this ambiguity has caused any real confusion in scientific discourse.

Still, as we learn more about moons in our own Solar System and also moons in other star systems, I think the I.A.U. will eventually have to come up with an official definition. And that brings me to the third and final thing I wanted to cover today: exomoons.

An exomoon would be defined as a moon (whatever that is) orbiting a planet or other planetary body outside our Solar System. Finding exoplanets is hard enough, so as you can imagine, searching for exomoons really stretches the limits of current telescope technology. But astronomers are trying, and next month (October, 2017) the Hubble Space Telescope will be making special observations of a planet named Kepler-1625b in an attempt to confirm a possible exomoon detection.


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.