Touring Proxima Centauri’s Asteroid Belts

Hello, friends!

As you know, sometimes things don’t go according to plan.  For today’s post, I was planning to draw a really pretty picture of a really planet—a planet that astronomers may (or may not) have found in the Proxima Centauri system.  But as I did my research about this possible planet, I realized I needed to draw something else for you first.

As reported in this 2017 paper, temperature readings indicate that Proxima Centauri may have at least one and as many as three asteroid belts.  Based on what I’ve read, it sounds like the presence of these belts has not been definitively proven yet.  But no one seems to be able to definitively disprove them either.

So here is a map of everything we currently know or suspect exists in the Proxima Centauri system.

As you can see, the planet Proxima b is in an extremely tight orbit around its star.  But since Proxima Centauri is much smaller and cooler than our Sun, Proxima b is technically in the star’s habitable zone.  Click here for my post on whether or not Proxima b could actually support life.

Beyond the orbit of Proxima b, we find our first possible asteroid belt.  In that 2017 paper I cited above, this innermost belt is described as the warm dust belt.  It appears to be located approximately 0.4 AU away from its star (roughly equivalent to the orbit of Mercury in our Solar System).

A little farther out, we find a second possible asteroid belt, which the authors of that 2017 paper describe as the cold dust belt.  Remember: we suspect these dust belts exist because of temperature measurements, hence the names.  The cold dust belt appears to be spread out between 1 AU and 4 AU (roughly equivalent to the space between the orbits of Earth and Jupiter in our Solar System).

And then farther out still, there appears to be a third belt, referred to as the outer dust belt (in my opinion, it should have been named the colder dust belt).  The outer dust belt appears to be located approximately 30 AU away from its star (roughly equivalent to the orbit of Neptune).

I want to emphasize again: as far as I can tell from my own research, no one has definitively proven or disproven these dust belts exist.  All we have are some temperature measurements that suggest something might possibly be there.

But if all those dust belts do exist, that tells us there should be planets orbiting in the gaps between the belts.  It would take a planet’s gravity to keep those gaps empty.  And now that you know that, I think we’re ready to take a closer look at Proxima c.

Except tomorrow is Insecure Writer’s Support Group day, so our trip to Proxima c will have to wait.  But I promise the wait will be worth it.  Science predicts that if Proxima c really exists, it must be the most gorgeous planet you’ve ever seen!

Next time on Planet Pailly, the unexpected benefits of having your manuscript edited.

Sciency Words: The Yarkovsky Effect

Hello, friends!  Welcome to Sciency Words, a special series here on Planet Pailly where we talk about those weird and wonderful words scientists use.  Today on Sciency Words, we’re talking about:

THE YARKOVSKY EFFECT

Have you ever tried to count all the stars in the night sky?  Well, that might be an easier job than finding and tracking all the asteroids that keep whizzing by our planet.  Part of the problem is due to something called the Yarkovsky Effect.

Ivan Yarkovsky was a Polish engineer working in Russia.  He was also a huge science enthusiast.  If Yarkovsky were alive today, I imagine he’d be writing a blog about all the cool sciency research he was doing in his free time.

But it was the late 19th/early 20th Century.  Blogging wasn’t an option, so instead Yarkovsky wrote pamphlets about science, which he circulated among his science enthusiast friends. And almost fifty years after Yarkovsky’s death, an Estonian astronomer by the name of Ernst Öpik would remember reading one of those pamphlets.

Imagine an asteroid orbiting the Sun.  Sunlight causes this asteroid’s surface to get hot.  Then, as the asteroid rotates, that heat energy radiates off into space.  Would this radiating heat produce any thrust?  Would there be enough thrust to push an asteroid off its orbital trajectory?

Öpik thought so, and in 1951 he wrote this paper introducing the idea to the broader scientific community.  Today’s Sciency Words post would probably have been about the “Öpik Effect,” except Ernst Öpik was kind enough to give credit to the obscure blogger pamphlet writer who originally came up with the concept.  Thus we have the Yarkovsky Effect.

And in 2003, radar observations of the asteroid 6489 Golevka confirmed that the Yarkovsky Effect is real!  The asteroid had wandered 15 km away from its original course!

Around the same time, a copy of Ivan Yarkovsky’s original pamphlet was found in Poland.  As described in this article, it seems Yarkovsky was working on the basis of some faulty premises and a few rather unscientific assumptions.  He more or less stumbled upon the right idea by accident (but let’s not dwell on that part of the story).

Next time on Planet Pailly, no one’s going to name a scientific theory after me, but maybe there’s another sciency honor I can aspire to.

Sciency Words: The Torino Scale

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 TORINO SCALE

Are you worried about an asteroid or comet smashing into Earth and annihilating human civilization?  Well, you should be worried about that a little bit.  But only a little bit.  Let me tell you about the Torino Scale, and while that won’t put all your fears to rest, it may help put things in perspective.

In the late 1990’s, M.I.T. Professor Richard Binzel came up with a system which he initially called the Near Earth Object Hazard Index.  In 1999, Binzel presented his system to a conference on Near Earth Objects (N.E.O.s) in Torino, Italy.

People at that conference loved Binzel’s idea and voted that the system should be adopted by the scientific community at large. They also voted to rename Binzel’s system the Torino Scale.

The Torino Scale asks two questions about any given N.E.O.: how likely is it to hit us, and how much destructive energy would be released if it did?  Taking those two factors into consideration, the Torino Scale then produces a score between zero and ten.  Zero means we have nothing to worry about.  Ten means “WE’RE ALL GONNA DIE!!!  AAAHHHHHH!!!” as the experts would say.

According to Wikipedia, the comet that caused the Tunguska Event would have probably scored an eight, and the asteroid that caused the K-T Event (the event widely believed to have killed off the dinosaurs) would have scored a ten.  Wikipedia also tells me that the 2013 Chelyabinsk meteor would have scored a zero, because while that particular N.E.O. was definitely on a collision course with Earth, it’s destructive energy was relatively low (I wonder if the residents of Chelyabinsk, Russia, agree with that assessment).

As of this writing, there are no known N.E.O.s that score higher than zero on the Torino Scale, as least not according to this website from NASA’s Jet Propulsion Laboratory.  It is possible for an N.E.O.’s threat level to change as we learn more about it.  As explained in this article from NASA:

The change will result from improved measurements of the object’s orbit showing, most likely in all cases, that the object will indeed miss the Earth. Thus, the most likely outcome for a newly discovered object is that it will ultimately be re-assigned to category zero.

Sooner or later, another eight, nine, or ten on the Torino Scale will come along.  Fives, sixes, and sevens could also be bad news for us.  But for now, at least within the next one hundred years, it sounds like we probably don’t have too much to worry about.

Probably.

Didymos, Didymoon, and Didy-me

I’m a huge space enthusiast and science enthusiast, but I am not an actual scientist.  I’m an outsider looking in, drooling a little as I watch all those real scientists doing all that real science.  But even as an outsider, I still sometimes get the chance to contribute in my own small way to the cause of science and space exploration.

Coming up in June of 2018, the Didymos Observer Workshop will be held in Prague, Czeck Republic.  For those of you who don’t recognize the name, Didymos is a large asteroid with an orbit that sometimes brings it alarmingly close to Earth.  It’s also one of those asteroids that has its own tiny moon, a moon which is informally known as “Didymoon.”

The Didymos Observer Workshop will be discussing the upcoming AIDA mission, a joint venture between NASA and ESA.  According to the workshop’s website, “AIDA will be the first space experiment to demonstrate asteroid impact hazard mitigation by using a kinetic impactor to deflect an asteroid.”  In other words, we’re going to whack Didymoon really hard to see how much we can change its orbit around Didymos.

Honestly, I feel a little bad for Didymoon, but the results of this experiment will help us prepare for the day when we need to smack an incoming asteroid off of a collision course with Earth. This is important for science, and someday it may save a whole lot of lives.

And I am really, really proud to say that one of my drawings is being used (with permission, of course) in the Didymos Observer Workshop’s promotional material.  Click here to check it out!

Sciency Words: Triangular Trade

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: Frost Line (An A to Z Challenge Post)

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, F is for:

FROST LINE

They say it’s cold in space. That’s not quite true. First off, how do you define what temperature means in a vacuum? That’s a much harder question that you might think.

But secondly—and more importantly for today’s post—a lot depends on where you are in space, because if you happen to be anywhere near a star, I guarantee you will feel the heat.

If you read enough scientific literature about space, you’ll eventually encounter the term “frost line,” and you’ll probably be able to guess from context what it means. Objects on one side of the line are close enough to the Sun for ice to melt (or more likely, sublimate), while objects on the other side are far enough away that ice remains frozen.

In our Solar System, the frost line is usually placed somewhere in the middle of the asteroid belt.

But there’s a lot of disagreement about where specifically the frost line is, in large part because there’s a lot of disagreement about how, specifically, the term should be defined.

Some astrophysicists define the frost line based on temperature conditions in the Solar System today. Others define it based on conditions from back when the Solar System was still forming. Also, there can be different frost lines for different chemicals, because the freezing point of water is different than that of methane or nitrogen or carbon dioxide.

This is a case of how some scientific terms are more clearly and precisely defined than others. And yet despite all the ambiguity about the frost line (or lines), it is still an incredibly useful term to help describe the layout of the Solar System. Which is why, if you read enough scientific literature about space, you are bound to come across this term eventually.

Next time on Sciency Words: A to Z Challenge, where did the word gravity come from?

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

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, C is for:

CENTAUR

As I mentioned in my first Sciency Words: A to Z Challenge post, some scientific terms are kind of dumb. This isn’t one of them. I actually think this one’s pretty clever. There’s a class of large objects in the Solar System that astronomers have decided to call centaurs.

Eh… no. These objects have nothing to do with horses, but they are sort of half one thing and half another! When they were first discovered, astronomers were confused because centaurs appeared to have the characteristics of both asteroids and comets.

I first learned about centaurs in this article from Discovery News. It’s now believed that centaurs originally came from the Kuiper belt—a sort of second asteroid belt that lies beyond the orbit of Neptune. Basically, they came from Pluto’s neighborhood.

Due to gravitational interactions with the gas giants, these objects were pulled inward. The now have highly unstable orbits crossing between the orbits of Neptune and Jupiter. Eventually, further gravitational interactions may hurl a centaur into the inner Solar System, putting it within melting distance of the Sun and transforming it into a full-fledged comet.

Originally, the International Astronomy Union wanted to name all the centaurs after actual centaurs from Greek mythology. But they quickly ran out of names. Now the official naming theme includes all mythical hybrids and/or shape-shifters. Examples include Typhon (half man, half dragon), Ceto (half woman, half sea monster) and Narcissus (a man who transformed into a flower).

Next time on Sciency Words: A to Z Challenge, we’ll find out why dimetrodon is not a dinosaur.

Sciency Words: Frost Line

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.

Sciency Words: Apollos and Atens

Sciency Words BIO copy

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 we’ve got two terms:

APOLLOS and ATENS

Asteroid are classified into different “groups” based on their orbital properties. The Apollo asteroids and Aten asteroids are two such groups, and these groups are of particular interest to anyone who doesn’t want a repeat of the K-T Event (which wiped out the dinosaurs) or the Tunguska Event (which flattened a forest and could have done the same to a whole city).

Technical Definitions

  • Apollo asteroids have a semimajor axis greater than 1.0 AU and a perihelion less than Earth’s aphelion of 1.017 AU. The first known Apollo was 1862 Apollo, for which the group is named.
  • Aten asteroids have a semimajor axis less than 1.0 AU and an aphelion greater than Earth’s perihelion of 0.983 AU. The first known Aten was 2062 Aten, for which the group is named.

Less Technical Definition

  • Apollo asteroids spend most of their time beyond Earth’s orbit, but cross inside at some point.
  • Aten asteroids spend most of their time inside Earth’s orbit, but cross outside at some point.

nv25-apollo-and-aten-orbit-diagrams

The important thing to know is that both Apollos and Atens cross Earth’s orbit at some point. Keep in mind that space is three-dimensional, so their paths don’t necessarily intersect with Earth’s. They might pass “above” or “below” Earth, so to speak.

But the orbits of enough Apollos and Atens do intersect with Earth’s orbital path that they might one day hit us. Atens are particularly worrisome. They spend so much time inside Earth’s orbit, in relatively close proximity to the Sun, that it’s hard for astronomers to find them.

So if a giant asteroid ever does sneak up on us and wipe out human civilization, my guess is it’ll be an asteroid from the Aten group. Those are the asteroids that frighten me the most.

nv25-aten-asteroid

Don’t Panic: It’s Just Another Asteroid

People ask me all the time: “Hey, did you hear about that asteroid?” These people then tell me about some asteroid that’s supposed to “just barely miss us” is the next day or so. Sometimes, they also ask, “Aren’t you worried?”

There are certain kinds of space news that I simply can’t get excited about anymore. This is one of them. Why?

nv23-asteroid-flybys

There’s actually a newsletter about asteroid flybys. It’s called Daily Minor Planet, and I have a subscription (it’s free). Every day in my inbox, I’m notified of the latest asteroid or other object skimming past Earth. Every day. Sometimes there are more than one per day.

Occasionally, one of these objects will pass within the radius of the Moon’s orbit. That’s not an everyday thing, but still… it happens more often than you might think.

So when people ask if I’ve heard about the latest asteroid flying past Earth, the only thing I can really say is, “Which one?” And if someone asks me if I’m worried, my answer is no. The asteroids that make headlines on the news and the asteroids that appear in Daily Minor Planet… those are asteroids we know about. It’s all the asteroids we don’t know about that scare the bejesus out of me.