Sciency Words: Clarke Orbit

November 2, 2018

Welcome to another episode of Sciency Words, a special series here on Planet Pailly where we take a closer look at the defintions and etymologies of science or science-related terms so we can expand our scientific vocabularies together.  Today’s term is:


So I was once again flipping through my copy of Brave New Words: The Oxford Dictionary of Science Fiction when I discovered a small fact that gave me a big surprise.  It involved Arthur C. Clarke, the legendary science fiction writer who’s best known for co-writing the screenplay of 2001: A Space Odyssey, but who was also a prominent thinker, futurist, and inventor.

In 1945, Clarke wrote this article for Wireless World describing a method for transmitting radio and television signals to the entire globe.  Clarke’s idea involved placing artificial satellites in a very specific and somewhat peculiar orbital arrangement.  Clarke explains:

It will be observed that one orbit, with a radius of 42,000 km, has a period of exactly 24 hours.  A body in such an orbit, if its plane coincides with that of the equator, would revolve with the earth and would thus be stationary above the same spot on the planet.

Clarke admits that this idea may sound a little too fantastical to some, but he argues that it’s entirely plausible to do this using current (as of 1945) technology.  His only concern was whether or not radio transmissions would be able to penetrate Earth’s ionosphere, though he was confident that at least some radio frequencies would work.

And of course Arthur C. Clarke was right (he usually was about these sorts of things).  We now know this orbital arrangement as a geosynchronous orbit, or to be more specific a geostationary orbit.  A geosynchronous orbit allows a satellite to move around in Earth’s sky, so long as it always returns to the same positions at the same times of day. A geostationary orbit does not allow a satellite to move at all in Earth’s sky.

And according to Brave New Words, these kinds of orbits are also known as Clarke orbits.

So which term should we be using?  Personally, I’m not sure.  I like how the term Clarke orbit honors Arthur C. Clarke for inventing the idea.  On the other hand, I appreciate how the term geostationary orbit helps define itself, thus making verbal communication a little easier.

So which of these terms would you prefer? Clarke orbit or geostationary orbit?

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:


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.

Hooray for Citizen Scientists!

April 30, 2018

In last week’s episode of Sciency Words, we met “Steve” and learned how this strange and unexpected aurora-like phenomenon ended up with such a friendly, normal-sounding name.  But there’s another important aspect of Steve’s story that I didn’t really touch on: the role of citizen scientists.

Photo of “Steve” by Elfie Hall, courtesy of Wikipedia.

Toward the end of this paper from Science Advances, the same paper which linked Steve to another aurora-related phenomenon known as S.A.I.D., I found a paragraph that I feel is interesting enough and important enough to quote in full:

STEVE has highlighted the importance of citizen science.  Although independently observed previously by auroral photographers both amateur and professional, citizen science has proven to be a bridge between amateur observers and traditional aurora scientists.  This bridge has facilitated the advancement of our understanding of both the night sky and magnetosphere-ionosphere coupling.  We emphasize that this collaboration with the citizen scientists was not simply through crowdsourcing and image analysis of a large data set. Citizen scientists discovered a new category of auroral observation by synthesizing complex information and asked the scientific community for input on these observations.  This example can help change the nature of scientific engagement between the scientific community and citizen scientists and move communication from one way to two way, with curiosity transitioning to participation and finally to stewardship.

Citizen science is often portrayed as something new, something that’s only become possible thanks to computers, the Internet, and technology in general.  And I think that’s fair.  The mystery of Steve might not have been investigated as thoroughly as it has been, or it might not have been investigated at all, if not for Facebook.

For most of the 20th and early 21st Centuries, cutting edge science has required a lot of extremely powerful, extremely sensitive, and extremely expensive equipment.  If modern science is seen as inaccessible to the average person, that might be in part because the average person could not afford to perform science him or herself.

But it wasn’t always so.  Most of the great scientists of the 17th, 18th, and 19th Centuries were essentially hobbyists, people who indulged their curiosity using the kind of tools they either bought off the shelf or built with their own hands.

So in a way, I think of citizen science as science returning to its roots, with ordinary men and women contributing once more to the important discoveries of our time (like the discovery of Steve).

Sciency Words: Steve

April 27, 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:


In 2014, photographer, citizen scientist, and weather enthusiast Chris Ratzlaff was out looking for the aurora borealis when he saw something weird in the sky.  Something that looked like an aurora but could not possibly be an aurora.

For one thing, it was in the wrong part of the sky.  It was too far south, well outside the auroral oval, the region encircling the pole where, on any given night, aurorae are predicted to occur.

And for another thing, this mysterious something was the wrong color.  It was purple. Now I was a bit confused about this part at first, because I thought purple was one of the normal colors in an aurora (along with green).  But aurora purple is more of a reddish or magenta-ish purple, whereas this new phenomenon was a true purple.  A purplish purple, so to speak.

According to this interview with Canadian Geographic, Chris shared pictures of the whatever-it-was on a Facebook group called Alberta Aurora Chasers.  Other members of the group then went out and got more photos.  Hundreds of photos.  And time-lapse sequences.

But still, nobody knew what this purple thing was.  An early guess that it was something called a proton arc got shot down by an expert, at which point Chris wrote “[…] until we know what it is, let’s call it Steve.”  This was a reference to the DreamWorks Animated film Over the Hedge.

In the film, a group of animals are confused and alarmed by the appearance of a neatly-trimmed hedge.  One of the animals says, “I would be a lot less afraid of it if I just knew what it was called,” to which another animal replies, “Let’s call it Steve!”

This bit about being less afraid of a thing simply because you know its name is, in my view, a profoundly true statement about the power of language.  But I digress.

According to this research paper from Science Advances, we now know, thanks to all those photos and time lapses from the ground, combined with satellite observations from orbit, what “Steve” is.  Or at least we know that it’s associated with another phenomenon called an S.A.I.D. (SubAuroral Ion Drift). Thanks to Steve, we now have a new way to observe and study S.A.I.D.s and learn more about the interaction between the solar wind and Earth’s magnetic field.

As such, Steve has been assigned a more proper-sounding scientific name: Strong Thermal Emission Velocity Enhancement (or S.T.E.V.E. for short).

Sciency Words: Polygon Terrain

March 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:


This phenomenon goes by several different names: polygon terrain, polygon patterned terrain, polygonal patterned ground formations… you get the idea. For the purposes of this blog, I’m making polygon terrain the official way to say it, because that matches up with other terrain-related terms we’ve seen, like chaos terrain or cantaloupe terrain.

Polygon terrain is a distinctive pattern of either cracks or ridges that draw polygonal shapes across the landscape. On Earth, these polygons tend to appear in arctic climates. They’re caused by the repeated freezing and thawing of underground glaciers.

When the ice thaws, the ground above it can sink down a little. Then when it refreezes, the ground is forced back up. Overtime, the surface starts to break and crack, producing a landscape that looks like this:

Images courtesy of Wikipedia.

Polygon terrain seems to be uncannily common in Mars’s northern hemisphere, in regions such as Utopia Planitia. This suggests two things:

  • There are large glaciers buried beneath the layers of surface dust and surface rock.
  • Those glaciers periodically thaw and refreeze.

Thawing Martian glaciers might or might not produce liquid water. Instead, the ice may sublimate, skipping its liquid phase and turning directly into water vapor. But still, during warmer seasons, it’s possible we might find a trickle of liquid beneath these polygon terrain regions—perhaps even enough to sustain a few extremophile microorganisms.

In the future, human explorers on Mars may take a keen interest in Mars’s polygon terrain. This kind of surface geometrization may not have anything to do with advanced alien civilizations, but it’s still worth a look if you’re searching for simpler forms of alien life. Or at least, it’s a good place to check if your colony is in desperate need of liquid water.

P.S.: For a slightly more detailed (without being unintelligibly technical) discussion of polygon terrain, please check out this post from Planetary Geomorphology Image of the Month.

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:


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.

Mars-y Christmas!

December 25, 2017