Tag: Pluto

Sciency Words: Pandemic

~ J.S. Pailly ~ 11 Comments

Hello, friends!  Welcome to this week’s episode of Sciency Words, a special series here on Planet Pailly where we talk about the definitions and etymologies of scientific terms.  Today’s Sciency Word is:

PANDEMIC

I normally write about space stuff.  Life on Mars, Pluto’s planet status… things like that.  But I thought I’d change things up a bit and talk about a medical science thing.  Why?  Oh, no particular reason.

In 1666, English physician Gideon Harvey wrote a book called Morbus Anglicus.  According to the Oxford English Dictionary, that book includes the earliest known usage of the word pandemic.

Pandemic comes from two Greek words meaning “all” and “people.”  For Gideon Harvey, it seems that pandemic diseases (leprosy, the bubonic plague, and most especially tuberculosis) are diseases that afflict all people, regardless of social status.  At least that’s my inference after reading the first chapter of Morbius Anglicus.

In modern usage, the meaning of the word pandemic has changed.  The World Health Organization (W.H.O.) and the Centers for Disease Control and Prevention (C.D.C.) use several different terms to categorize disease levels.  According to this online textbook from the C.D.C., those terms include:

  • Endemic: a level of disease that is normal for a given population.
  • Outbreak: a sharp increase above the endemic level of a disease within a geographically small area.
  • Epidemic: a sharp increase above the endemic level of a disease within a geographically large area.
  • Pandemic: an epidemic that is no longer geographically contained, i.e.: an epidemic that has crossed national borders or spread from one continent to another.

Those may seem like clear, straightforward definitions on paper, but according to several sources (like this one or this one or this one), that official definition for pandemic may be inadequate.  Lots of diseases cross national borders.  Lots of diseases hop from continent to continent.  The W.H.O. and the C.D.C. don’t issue pandemic alerts every time this happens.

The problem apparently came to a head in 2009 with the H1N1 swine flu.  Yes, swine flu was crossing borders, but public health officials started quibbling over whether swine flu was new enough or infectious enough or deadly enough to qualify for pandemic status.  Those qualifiers aren’t included in the official definition, but for a lot of people, it feels like they should be.  Otherwise, the seasonal flu would be a pandemic.

Now I’m not particularly well versed in medical science, so allow me to end this post by talking about a space thing.  In the early 2000’s, astronomers started arguing about whether Pluto was truly a planet.  This led to the International Astronomy Union issuing a new, more detailed definition of the word planet (and nobody had an argument about Pluto ever again).

Based on everything I read while researching this post, I feel like a similar story is unfolding over the word pandemic.  Perhaps, as scientists learn more about the spread of infectious diseases in our modern, globalized society, a new, more detailed definition for pandemic will emerge (and I’m sure it will be as universally accepted as the I.A.U.’s planet definition was).

Next time on Planet Pailly, it’s time to reveal my theme for this year’s A to Z Challenge.

Sciency Words: Barycenter

~ J.S. Pailly ~ 11 Comments

Hello, friends!  Welcome to Sciency Words, a special series here on Planet Pailly where we talk about those big, complicated words scientists use.  Today’s Sciency Word is:

BARYCENTER

Excuse me, but I’m going to do that “um, actually” thing that people who think they’re really smart like to do.  Now you may think the Earth orbits around the Sun.  Um, actually… the Earth and Sun both orbit something called the barycenter.

The word barycenter comes from two Greek words meaning “heavy” and “center,” and it refers to the common center of mass for two or more celestial bodies.  Based on sources I found via Google Ngrams, the term started appearing frequently in astronomical journals during the early 20th Century, and it may have been in use as early as the 1880’s.

Let’s say you have two celestial bodies.  One is really massive, the other is much less massive.  In that case, the barycenter will probably be located somewhere inside the more massive object.  This is the case for the Earth and her Moon.  Based on numbers I got from Wikipedia, the Earth-Moon barycenter is about 1000 miles (1700 km) beneath Earth’s surface.  Or to measure that a different way, the barycenter is about 3000 miles (4600 km) away from the center of the Earth.

Now let’s say you have two celestial bodies of roughly equal mass.  In that case, the barycenter will be located somewhere between them.  Something like this has happened with Pluto and his giant moon, Charon.  Once more using numbers from Wikipedia, it looks like the Pluto-Charon barycenter is about 500 miles (960 km) ABOVE the surface of Pluto.

As for the Earth-Sun barycenter, it’s located deep inside the Sun.  So if you say Earth orbits the Sun, you’re not too far from the truth.  But of course Earth is not the only planet in the Solar System, and when you consider the Solar System as a whole, you’ll find the Sun wibbles and wobbles about in weird, loopy patterns.  As you can see in the highly technical diagram below, the Sun wibbles and wobbles so much it can wobble into a totally new position in just a few years.

Click here for an actual diagram of the Sun’s movement relative to the Solar System’s barycenter.

As explained in this paper, this is mainly due to the gravitational influences of Jupiter and Saturn. Over longer time scales (centuries rather than decades), the subtler influences of Uranus and Neptune also have a noticeable effect.

So the next time someone tells you the Earth orbits the Sun, you can do the “um, actually” thing and explain what a barycenter is.  Trust me, it’s a great way to sound smart and make lots of new friends!

Next time on Planet Pailly, what did people in 1962 think we’d find on other planets?

Sciency Words: Ice

~ J.S. Pailly ~ 6 Comments

Sciency Words: (proper noun) a special series here on Planet Pailly focusing on the definitions and etymologies of science or science-related terms.  Today’s Sciency Word is:

ICE

I have a friend who teases me whenever I use the word ice. This is because, depending on what we’re talking about, I can’t just say “ice.”  As soon as the conversation turns to space stuff (as it often does when I’m around, for some reason), I feel the need to say “water ice.” I feel the need—no, the compulsion to specify that I mean the frozen form of water, as opposed to the frozen form of something else.

In more normal, down-to-earth sorts of conversation, I don’t feel that same compulsion.  Water ice is the only kind of ice we’re likely to encounter here on Earth. On rare occasions, if you’re at a science fair, or maybe a Halloween party, you might encounter carbon dioxide ice (a.k.a. dry ice).  But that’s a very rare special case.

However, as soon as we start talking about other planets and moons, or comets and asteroids, the word ice takes on a much broader meaning. In these more cosmic conversations, you really do need to be specific about which ice you’re talking about. To quote from a recent issue of The Planetary Report:

In the strictest definition, ice is the solid form of water.  However, planetary astronomers often use “ice” to refer to the solid form of any condensable molecule.

Beyond Earth, and especially in the outer Solar System, we find all sorts of crazy ices, like ammonia ice, methane ice, or nitrogen ice.  Along with the water ice and CO2 ice we Earthlings are more familiar with, these ices make up the hard crusts of many planetary bodies, like Titan or Pluto.

We also find ice crystals (of various types) forming in the clouds of planets like Uranus and Neptune.  In fact, Uranus and Neptune are often called “ice giants” in large part because of all those weird ices found in their atmospheres.

Starting next week, I’m planning to take a much closer look at those ice giant planets.  I expect my research to turn up plenty of questions, but very few answers.  Uranus and Neptune are, at this point, the least well explored planets in the Solar System.

So stay tuned!

P.S.: I want to start referring to all forms of igneous rock as “magma ice.”  After all, what is igneous rock but frozen magma?  I can’t think of any good reason why the term “magma ice” shouldn’t apply.

Sciency Words A to Z: Tholin

~ J.S. Pailly ~ 3 Comments

Welcome to a special A to Z Challenge edition of Sciency Words!  Sciency Words is an ongoing series here on Planet Pailly about the definitions and etymologies of science or science-related terms.  In today’s post, T is for:

THOLIN

Have you ever been stuck trying to say something, but you just don’t have the right words to say it?  In the 1970’s, planetary scientists Carl Sagan and Bishun Khare had that problem.

They’d conducted a series of experiments using gaseous chemicals that were known to be common in outer space, chemcials like ammonia, methane, water, hydrogen sulfide… they mixed all these chemicals together and zapped them with either an electric spark or ultraviolet light.  Then they studied the orangey-brown gunk that formed as a result.

Initially, this gooey gunk was thought to be a polymer, but as reported in this 1979 paper, Sagan and Khare soon determined that wasn’t what it was.

It is clearly not a polymer—a repetition of the same monomeric unit—and some other term is needed.

Sagan and Khare propose the word “tholin,” which is sort of a pun.  It’s taken from two Greek words that are spelled the same, except for an accent mark that’s shifted from one vowel to another.  One word means “muddy,” the other means “dome” or “vault,” as in the great dome or vault of the sky.  Sagan and Khare go on to mention that they were “tempted by the phrase ‘star-tar.’”

Tholin may be present on some asteroids and comets, and tholin or tholin-like material has been observed on several moons in the outer Solar System, most notably Titan.  We may have even found tholin on Pluto, and several other red-hued dwarf planets could have it too.

So what specifically is this stuff?  Well, I can’t really say.  Tholin is not a specific substance but rather a general category of organic matter.  As planetary scientist Sarah Hörst explains in this article:

The best analogy I have been able to come up with is “salad.”  Salad, like tholin, is a mixture of a number of different compounds and spans a fairly broad range of materials.  Most of us would agree on a case by case basis whether or not something is a salad, but the definition is not at all specific and the material itself depends on the starting materials, temperature, etc.

So there are many different tholins out there.  The tholin we might find inside a comet is probably different from the tholin we find on Pluto, which is different from the tholin we find on Titan.  What all these tholins have in common is that they’re the kind of yucky gunk you’d expect life to make, except life didn’t make it.

However, while life doesn’t make tholin, tholin could, in theory, be used to make life.  Or at least, once life gets started, tholin can serve as a source of food for primitive microorganisms.

Titan has long been the poster child for tholin chemistry, simply because Titan has so much of this stuff.  More than enough, you’d think, for some sort of biological activity to get started—assuming it hasn’t already!  However, with all that tholin lying around, sending astronauts to explore Titan properly may prove to be a sticky proposition.

Next time on Sciency Words A to Z, there’s no way we’ll find life on Venus… right?

Sciency Words: Nominal Solar Radius

~ J.S. Pailly ~ 6 Comments

Sciency Words: (proper noun) a special series here on Planet Pailly focusing on the definitions and etymologies of science or science-related terms.  Today’s Sciency Word is:

THE NOMINAL SOLAR RADIUS

Last week, I told you about the classification system in use for main sequence stars. Today we’re going to talk specifically about G-type stars.  Or rather, we’re going to talk about one G-type star in particular: the Sun.

I was recently clued in on a controversy about the Sun.  After reading up on the issue, though, I don’t think this is a real controversy.  It’s more like an Internet controversy.

If you’ve ever wondered how big the Sun is, a quick Google search will get you an answer.  But it won’t get you the correct answer.  That’s because we apparently do not know precisely how big the Sun is.  As this paper from 2018 states: “[…] measuring with high accuracy the diameter of the Sun is a challenge at the cutting edge of modern techniques.”

Part of the problem is that we’ve tried using multiple methods for either measuring the Sun’s radius by direct observation or by calculating the radius based on other kinds of measurements.  And we keep getting different answers.  I take it we’re not getting wildly different answers, but there’s enough variation there to create a problem for scientists who study the Sun.

So here’s where the alleged controversy comes in.  Our friends at the I.A.U.—the International Astronomy Union, the same organization that decided Pluto is not a planet—decided a few years ago what the Sun’s radius should be.  They said it equals 695,700 km.  No more, no less.  I mean, who are these people to decide what is or is not a planet?  Who are these people to decide now how big the Sun is?

Except that’s not actually what the I.A.U. did. Regardless of how I may feel about the whole Pluto thing, I do agree with the I.A.U. about their definition of the solar radius.  Or to speak more precisely, I agree with their definition of the nominal solar radius.  As explained in the I.A.U. resolution on this matter:

These nominal values should be understood as conversion factors only—chosen to be close to the current commonly accepted estimate […] not as the true solar properties.  Their consistent use in all relevant formulas and/or model calculations will guarantee a uniform conversion to SI units.

So I don’t think the controversy, such as it is, really exists.  If we’re going to use the nominal solar radius as a unit of measure, we all have to agree about what that unit of measure is equal to—especially because we still don’t know what the actual solar radius is.

Feel free to bash the I.A.U. about Pluto, if you want, but when it comes to their nominal solar radius definition, I think the way they handled it makes a lot of sense.

Book Recommendation: Chasing New Horizons

~ J.S. Pailly ~ Leave a comment

If you’re a Pluto fan, this book is required reading.  Authors Alan Stern (who led the New Horizons Mission) and David Grinspoon tell us the story of why NASA neglected to send a space probe to Pluto for so long, and how an intrepid group of scientists fought for a Pluto mission and eventually won the day.

This is not just another book about science and technology.  Yes, a large portion of the book is about the technology it took to get to Pluto and the science we learned once the New Horizons space probe started sending back its data. But more importantly this is a David and Goliath story, with NASA’s bureaucracy cast in the roll of Goliath and the so-called “Pluto Underground” playing the roll of David.

I feel like the authors must have made a few enemies at NASA, and maybe a few enemies in Washington D.C. as well, for writing this book. This is an honest and forthright look at the kind of political and bureaucratic resistance New Horizons had to deal with.  As a space enthusiast, I keep hearing about other space missions that are struggling to get to the launch pad.  After reading Chasing New Horizons, I think I have a clearer idea of what causes these sorts of hold up.

And then there’s the elephant in the room: Pluto’s planet status.  The authors say very little about that, which in and of itself says a lot.

I’m guessing the authors made a few enemies at the International Astronomy Union as well.  They give us only a few pages about the I.A.U. vote to demote Pluto and why they believe that vote was wrong.

Overall, I highly recommend this book.  Five out of five stars, or maybe I should give it a rating of nine out of nine planets.

The Infamous “Pluto Not Yet Explored” Stamp

~ J.S. Pailly ~ 4 Comments

A couple years ago, I needed some postage stamps.  To my delight, the local post office had a wide selection of space-themed stamps to choose from, including this four-stamp sheet commemorating the New Horizons mission to Pluto.

But it wasn’t until I read Chasing New Horizons by Alan Stern and David Grinspoon that I realized the full significance of the stamps I’d purchased.  Those stamps were, in fact, a major part of New Horizon’s history.

The story begins in 1991, shortly after Voyager 2 completed its flyby of Neptune.  The U.S. Post Office issued a set of stamps honoring the first NASA space probes to visit each of the planets and also the Moon.  Pluto was also included in the set, with the caption “Pluto not yet explored.”

Apparently some in the planetary science community took this as a challenge.  That set of stamps, including the “Pluto not yet explored” stamp, became a symbol of work that had been left unfinished, of a job that still needed to be done.  The stamp was used in proposals and presentations arguing for a Pluto mission.  It was part of the public outreach campaign once New Horizons was underway. And the day New Horizons reached Pluto, a poster-sized version of the stamp was help up for the press with the words “not yet” crossed out.

So naturally, following that 2015 flyby mission, the Postal Service had to issue new stamps.  That day when I went to get stamps, so I could pay my rent and bills and other mundane things, I had no idea how much meaning and significance was packed into that little stamp sheet.  Even the elongated dash in “Pluto—Explored!” feels significant, as though it’s a reminder of the words that were crossed out.

I’ve never been a stamp collector, but as it so happens I still have at least one sheet of Pluto stamps left, and once I knew the full story behind them I went and did a little shopping online.  Now both sets of stamps—the 2015 stamps for New Horizons and the original set of stamps from 1991—are part of my modest collection of space exploration memorabilia.

New Horizons: The Road Goes Ever On

~ J.S. Pailly ~ 9 Comments

The New Horizons mission has been on my mind recently, in part because of my post last week on Ultima Thule, but also because I just started reading Chasing New Horizons: Inside the Epic First Mission to Pluto by Alan Stern and David Grinspoon.

New Horizons has already visited the most distant “planet” in the Solar System (Pluto was still considered a planet when New Horizons launched), and now it’s going to explore an object even more distant than that. And after that?  Onwards to interstellar space, just like Voyager I and Voyager II, to continue exploring the universe for us.

But as I said, all this has got me thinking about travel and exploration and discovery, and also strangely (or perhaps not so strangely) about J.R.R. Tolkien.  So today I’d like to share a piece of Tolkien’s poetry, something that fit nicely into The Lord of the Rings but also fits nicely (I think) into the ongoing saga of the New Horizons mission.

Sciency Words: Moon

~ J.S. Pailly ~ 20 Comments

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.

Sciency Words: Xena (An A to Z Challenge Post)

~ J.S. Pailly ~ 10 Comments

Today’s post is a special A to Z Challenge edition of Sciency Words, an ongoing series here on Planet Pailly where we take a look at some interesting science or science related term so we can all expand our scientific vocabularies together. In today’s post, X is for:

XENA

In January of 2005, astronomers at the Palomar Observatory in California discovered a new “planet.” Except this planet had a highly inclined (tilted) and wildly eccentric (non-circular) orbit. Pluto’s modestly eccentric, Neptune-crossing orbit was weird enough, but this? Planets aren’t supposed to have orbits like this, are they?

The Palomar Observatory astronomers decided to name their discovery Xena.

Personally, I think that name fits: a convention defying name for what was, at the time, a convention defying planet. But Xena was only intended to serve as a placeholder until the International Astronomy Union (I.A.U.) could assign an official name, and they chose the name Eris.

In Greek mythology, Eris was the goddess of discord. This name also seems fitting, given the amount of discord that would soon follow, because Eris was officially classified not as a planet but as a dwarf planet, along with Pluto.

There is now a proposal to reclassify Pluto, Eris, and about a hundred other Solar System objects as planets. It’s a proposal I like, for reasons I tried to lay out in a previous post, but it’s not something I expect to go anywhere. Most professional astronomers seem to be against it.

Anyway, the story of Xena/Eris is an example of something that seems to happen a lot in the field of astronomy. New discoveries get temporary names (pop culture references aren’t uncommon here) until the I.A.U. can review the discovery and assign a name officially.

As another example, the team behind NASA’s New Horizons mission came up with a ton of names for geological features on Pluto and its moon, Charon. Many of these names came from Star Trek, Star Wars, Doctor Who, Battlestar Galactica, The Lord of the Rings… apparently there are a ton of nerds at NASA. You can expect the I.A.U. to change most of those names—but perhaps not all of them. Sometimes a pop culture reference gets the I.A.U.’s okay (especially Lord of the Rings references, I’ve noticed).

In the case of Eris, Eris’s moon (originally named Gabrielle) was officially renamed Dysnomia. Dysnomia was the ancient goddess of lawlessness, and Lucy Lawless was the actress who played Xena on T.V. That was apparently an intentional, though rather convoluted, way to honor what could have been Xena: Warrior Dwarf Planet.

Next time on Sciency Words: A to Z, in the beginning there was the Big Bang. Then there was ylem. A whole lot of ylem.