
Earth is a ‘dwarf planet’ because it has not cleared its orbit - rbanffy
https://medium.com/@mtanne/turns-out-earth-isnt-a-planet-c06f5208d36e
======
DCKing
This is very misleading, and it looks to be intentionally so. The author
pretends that "cleared its orbit" means "cannot share its orbit with any sort
of rock". But that's not at all how "cleared its orbit" is defined.

The excellent Wikipedia page [1] on what "cleared its orbit" really means
should tell you enough. Firstly, this asteroid would be several magnitudes
below the amount of mass necessary to strip Earth from its status. Secondly,
due to this body being in orbital resonance with Earth its mass would not even
count towards the mass that Earth has not cleared out of its orbit. This also
counts for 3753 Cruithne, one of Earth's other known co-orbitals [2] which
we've known about for _years_ without making a fuzz, also because it has
insignificant mass and is in orbital resonance.

Given the tone of the article and how easily it can be falsified, it seems to
me the author is deliberately misleading his audience to push his nostalgia
for Pluto's planethood.

[1]:
[https://en.wikipedia.org/wiki/Clearing_the_neighbourhood](https://en.wikipedia.org/wiki/Clearing_the_neighbourhood)

[2]: [https://en.wikipedia.org/wiki/Quasi-
satellite#Earth](https://en.wikipedia.org/wiki/Quasi-satellite#Earth)

~~~
runarberg
Regardless of the validity of the premise, the conclusion—and the point—of the
article is valid. Debating over the definition of planets is silly. It feels
as if this is done just so school children can pass astronomy tests by
residing the names of all 8 planets. Otherwise there is no point in holding
this definition, or _any_ definition for that matter.

It is a known problem classifying most natural phenomena is at best
difficult—but most likely impossible—to do so under a simple definition. What
most naturalists do is to holding a set of common beliefs over what belongs in
which category. For example, there is no easy definition of a bird. Rather we
have a set of common beliefs over which animals can rightly be called a bird.
Worse, the set of “common beliefs” varies depending on field of interests.
Some people might talk about viruses as “living” because that servers their
purpose (it makes their work easier; it makes more sense) while other wont.

I hope that we soon stop this silly debate. Our definition of a planet will
not hold for long. The more planets we discover the weaker the current
definition will become (this is the authors point). When that happens I bet
people will talk about Pluto (and Eris, Sedna, etc.) as a planet just because
it matches peoples idea of what a planet is. Just like people talk about
viruses as living organisms just because it fits nicely into what we think
life is.

\---

edit: grammar

~~~
kevin_thibedeau
There are a multitude of objective measures that can be applied to planet
classification. In almost all of them, Pluto is an obvious outlier. The
controversy hype was manufactured by the press looking for a sensation.

~~~
runarberg
The same can be said about birds. You can say that for an animal to be
considered a bird it: a) has to have feathers, b) has to have warm blood, c)
cannot have claws on its wings, d) cannot have teeth. But than you find one
animals that we can all agree is a bird that has claws on its wings while
still a chick (will it grow up to become a bird?).

So you use a new definition. Bird are evolutionary descendant some reptiles
had contained feathers and warm blood. This will (mostly) hold out until we
discover some extinct groups of reptiles that had feathers and warm blood.

Note though how vague the latter definition is. It has to be. Because we
cannot derive at a solid definition of a bird that encapsulates all animals
that we can consent on calling a bird.

~~~
Retric
Except bird is not the scientific name it's Ornithurae which nobody cares
about. Planet on the other hand is from Astronomy (asteres planetai), so just
as Ornithurae means what scientists agree it means so does Planet. Electron
and planet are both in common useage, but nobody gets in a tizzy about it.

PS: This is just pure bike-shedding by people who only care about the trivia
and don't really use it for anything meaningful.

------
gus_massa
> [...] _and the intuition we all have that Pluto, is in fact, a planet._

It's not intuition, it's rote learning. Nobody cares if Eris is a planet or
not, because nobody memorized a list of planets that include Eris.

Eris is (apparently) slightly smaller than Pluto, but (apparently) the mass is
slightly bigger. So in any sane classification both are planets or neither.

The problem is that we don't know how many other object of similar size and
mass are out there. They are very difficult to detect, so probably there are a
few more to be discovered.

~~~
exDM69
Eris is slightly smaller but more massive than Pluto. The discovery of Eris
lead to the reconsideration of the definition of a planet.

There's a choice to be made, either Pluto, Eris, Haumea, Makemake and Ceres
are all planets or none of them are. And any new discoveries will be planets
too. Or we come up with some kind of non-scientific arbitrary choice that
Pluto is a planet because people on the internet got mad when it was changed
to a dwarf planet.

Out of the dwarf planets, Ceres is my favorite because of the ingenious
mathematics that lead to the determination of its orbit and thus verified that
it's a planet. There was only a week's worth of observations before the planet
went behind the sun and Carl Friedrich Gauss invented a method for initial
orbit determination from three observations and pioneered the method of least
squares to further refine the orbit to match the rest of the observations and
the planet appeared where predicted a year later.

At the time of discovery in 1801, Ceres was considered to be the 8th planet
(Neptune wouldn't be discovered for another 70 years). I don't know what
eventually caused Ceres to be demoted from its planet status (perhaps because
it's in the middle of the asteroid belt).

I think that dwarf planet is a suitable label to give Pluto. It's an
insignificant blot of dirt in the outer solar system, and there are probably
dozens like it waiting to be discovered.

~~~
ianburrell
The first four asteroids, Ceres, Pallas, Juno, and Vesta, were considered
planets until the 1850s when lots more asteroids were discovered.
[https://en.wikipedia.org/wiki/Ceres_(dwarf_planet)#Classific...](https://en.wikipedia.org/wiki/Ceres_\(dwarf_planet\)#Classification)

------
erikpukinskis
First they came for the Kuiper belt objects, and I said nothing because I do
not live on a Kuiper belt object...

------
chasing
This reads like an impassioned argument made by someone who doesn't really
know what he's talking about.

Scientists need to come up with terms for groups of things to help the process
of understanding them and communicating about them. If you're not a scientist
and want to call Pluto a planet or Earth a moon or the Moon a star or Uranus a
black hole -- I guess go for it, but recognize that it'll make having
conversations with learned people about those things more difficult.

It's like getting into an argument about whether an iPhone becomes a desktop
computer when you use it while it sits on your desk. Fine. Call it a desktop
computer, but you're just going to confuse everyone. "Yeah, you can only use
[Software X] on your desktop computer." "I tried but it totally didn't work!"
"What's your operating system?" "iOS." "That's not a desktop computer." "But
it's right here on my desk."

And scene.

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terravion
I love how the author accuses the IAU of an agenda, but then clearly has his
own--which doesn't seem to be nearly as grounded in taxonomic consistency.

~~~
_jal
I think part of the author's goal is pointing out that taxonomic consistency
is useless if you're using stupid criteria, and then arguing that the criteria
are stupid.

The second point is arguable, the first is not.

~~~
masklinn
> I think part of the author's goal is pointing out that taxonomic consistency
> is useless if you're using stupid criteria

Of course that falls down when the author is either misunderstanding or
misrepresenting the criteria.

------
simonh
This is only even a theoretical issue if 2016 H03 is both in a long term Earth
grazing orbit and is not gravitationally bound to it.

If it's only in a temporary orbital relationship with Earth on a geological
timescale, then it will eventually be cleared. If it's gravitationally bound
to Earth then it's just in an odd kind of orbit.

~~~
jamie_ca
Using this article's logic, Jupiter is not a planet either (it has two swarms
of asteroids hanging out around its L4 and L5 lagrange points).

~~~
simonh
Theyre gravitationally bound to Jupiter.

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awinter-py
If pluto becomes a planet again michael brown gets to write a new book called
'If I _had_ killed pluto this is how I would have done it'

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charles-salvia
This is kind of silly... this is really a problem with the human obsession
with creating taxonomies and classifications of natural phenomena, when
natural phenomena are basically collections of atoms that have very fuzzy
boundaries. Clustering algorithms are, in general, very subjective, and it's
no surprise that our scientific efforts to "cluster" everything often produce
counter-intuitive or undesirable results at certain boundary cases.

It's the same problem with biological taxonomies - is a lungfish a fish or an
amphibian? The reality is it doesn't matter apart from the artificial taxonomy
we impose on it so that our brains can better cope with the complexity of the
Universe.

Perhaps a better (but more annoying) way of classifying everything would be to
use hierarchically clustered taxonomies for everything, so that we could make
statements like "Earth is considered a planet if we cut the dendrogram at
level 5, but a dwarf planet if we cut at level 4, etc".

~~~
placebo
I completely agree. It's so silly that I chuckle every time this argument
comes up. Then again, people are so attached to their definitions and
classifications in a way that it becomes part of how they define themselves,
and therefore any suggested change is considered a personal threat. This of
course is not limited to planets...

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Mendenhall
This was interesting. If I am understanding correctly by the same "rules"
pluto was determined to not be a planet it now would apply to earth.

Quote from article "Asteroid 2016 H03 is proof that Earth has not cleared the
neighborhood around its orbit. Therefore, under the definition of a planet
vigorously defended by the IAU since the adoption of Resolution 5A on August
24, 2006, Earth is a ‘dwarf planet’ because it has not cleared its orbit,
which is the only criteria of their definition that Pluto fails."

"what planet are you on?.....trick question,you are not on a planet, youre on
a dwarf planet:)"

~~~
valuearb
No, this was written by someone who is sad about the redefinition of planet,
and so wrote this mis-leading piece about what constitutes clearing an orbit.
Jupiter, for example, has 100,000 trojan asteroids in it's orbit.

[https://en.wikipedia.org/wiki/Clearing_the_neighbourhood](https://en.wikipedia.org/wiki/Clearing_the_neighbourhood)

I don't think the definition is clear, but one asteroid ain't it. I do like
the idea of uberplanets.

~~~
SomeStupidPoint
How is he even pretending? The definition (as I recall and on wiki) is clearly
about comparable sized objects, and 100m vs 13,000,000m isn't very comparable.

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s_kilk
I'll never not be amused by how salty people get over Pluto being stripped of
its planet-hood.

------
geofft
"Planet" is a word. I have no intuition for what a "planet" is because I was
not born knowing English.

However, it seems intuitively true to me that Jupiter, Saturn, Uranus, and
Neptune are different sorts of things, whatever you want to call them, than
Mercury, Venus, Earth, Mars; that our moon is a different sort of thing from
all of those (and more like the moons of all of those); and that Pluto is
_probably_ closer to Mercury-Mars than to the moon, or Eris, or Ceres, or
anything else.

If you tell me that the appropriate label for Jupiter-Neptune is "planet" and
for Mercury-Mars, Pluto, and Eris is "dwarf planet," I'll accept that; those
sound like good categories. If you tell me that the appropriate label for
Mercury-Neptune is "orbinaut" and the appropriate label for Pluto and Eris is
"astrolith," I'll accept that too, those also sound like good categories. I
have no intuitive objection to either of those categorizations, and both seem
like they could be supported by evidence.

If you tell me that Mercury, Earth, Jupiter, Uranus, and Pluto are "oddballs"
and the rest are "evenballs," that seems intuitively wrong. But I don't think
anyone's proposing that!

~~~
termain
The terms are gas giant and terrestrial (or rocky) planet. They're already
there.

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Grue3
The point about extrasolar planets is great. Technically we can't say we
discovered an extrasolar planet because it's impossible to ascertain it has
cleared its neighborhood. It could easily be a dwarf planet.

------
Crito
"Planet" refers to points of light that have complex motion in the night sky
throughout the year. Earth is below the sky, therefore Earth cannot possibly
be a planet. This is just common sense people.

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shrikey
I am absolutely amazed by how many people have such a strong sentimental
attachment to Pluto. Forget about the clearing orbit requirement, even though
this article puts up very fallacious arguments, and instead considered that
Pluto is smaller than Mercury. Pluto is smaller than our moon. Pluto is not
even as wide as Asia. Pluto and Charon orbit a point outside Pluto's surface.

Oh, and then there's the thousands of Kupier Belt objects larger than Pluto.

Be true to something so Frozen, and let it go.

~~~
beambot
Why are you amazed?

These sort of taxonomical debates are exceedingly coming in biology (eg "is
this a new species or just another variant?", "how many base pair differences
are required to be a species?", Etc).

Taxonomy for planets and other celestial bodies is increasingly important as
we discover more and more exoplanets. And it turns out that writing a good
definition is hard... especially when we have so few exemplars in our own
solar system.

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here2day
Fake news! The most obvious give aways in the title being planet and orbits.
Earth is not a planet but a plane and it doesn't orbit anything as it is
stationary.

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rbanffy
I would prefer a definition based on how round the object is. If it's round or
a rotational ellipsoid close enough to a sphere, it's a planet.

~~~
mertd
Is the Moon a planet?

~~~
FreeFull
I was wondering before if it would count as a planet if it wasn't bound to
Earth. It is around 6 times more massive than Pluto. There are also other,
bigger moons in our solar system, such as Ganymede, which has about half the
mass of Mercury (but also has a bigger diameter, due to being significantly
less dense).

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spatulon
If Earth and Pluto were planets, clearly Gustav Holst would have written
movements for them as part of his Planets suite, but he did not.

Ergo, they are not planets.

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powera
Earth is a ‘dwarf planet’ because taxonomists are better at making useless
headlines than doing actual work.

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jccalhoun
What's in a name? That which we call a rose by any other name would smell as
sweet.

~~~
taneq
"A blegg by any other name..."

