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jimmy m
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15 Feb 2020, 9:26 am

Pluto was a planet in good standing for seventy-six years when in 2006, out of the blue, it was demoted and booted from our solar system’s family of planets. In 2006 it was demoted to a second class status and was given the designation as a "dwarf planet". Essentially it underwent a scientific character assassination and was discriminated against. It now has a second class citizen status.

There are three big reasons why the IAU’s decision, not Pluto, should be ditched.

One: “If you take the IAU’s definition strictly, no object in the solar system is a planet,” explains NASA planetary scientist Alan Stern. “No object in the solar system has entirely cleared its zone.” Even Earth’s neighborhood is cluttered with more than 20,000 asteroids – Near-Earth Objects (NEOs) – routinely threatening to hit us.

Two: the IAU definition is ambiguous, completely arbitrary – not based on scientific precedent – and specifically intended to discriminate against planetary diversity. There is not an objective, scientific reason to lock out worlds such as Pluto simply because they’re different than the eight country clubbers.

The truly impartial thing to do is admit that planets – like stars and galaxies – come in a far greater variety of sizes, appearances, and behaviors than we ever imagined.

Three: the IAU ratification process was not legitimate. The votes were taken during the assembly’s closing ceremonies, ****after*** most of its 2,500-plus attendees had vamoosed. Only 424 astronomers ended up voting, out of IAU’s 10,000 total members.

Sure, Pluto is a small, cold oddball. But thanks to the ongoing analysis of eye-popping photos and data from the New Horizons spacecraft that flew past it in 2015, we’re now learning that Pluto, with its five moons, is one of the most spectacular worlds in our solar system. It even looks to have key attributes possibly conducive to life, including water and organic chemicals.

“It’s more dynamic and alive than Mars,” says University of Central Florida planetary scientist Philip Metzger. “The only planet that has more complex geology is the Earth.”

For all of these reasons and others, I believe it’s high time for us to restore Pluto’s rightful place in the solar system and call it what it is: a planet!

Source: Why is Pluto no longer a planet? The answer may surprise you (here's why it also must change)


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naturalplastic
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16 Feb 2020, 5:36 pm

Nature doesn't always fit into our manmade boxes!



naturalplastic
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16 Feb 2020, 5:54 pm

But yes...you could fill both sides of the ledger with arguments.

On one hand Pluto may have been "a planet in good standing for 70 years". But for most of that time we didn't know what an undersized shrimp it is. We assumed that was as big as Mars, or at least as big as Mercury. It turned out to be smaller than Earth's own Moon. So this "planet in good standing" was an in fact "an imposter" some might argue.

Also ...if you reinstate Pluto to it's former rank as a planet then you also have to promote at least one, and maybe three other objects only recently discovered to the same rank. These are other "transneptunian objects" recently found that are even farther out than Pluto. Eris is slightly bigger than Pluto (though slightly less massive), and would also have to be designated a "planet". And possibly two other objects with Hawiian sounding names that Ive forgotten are also "dirty snowballs" in the same weight class as Pluto out in the outer reaches of the solar system.


So instead of restoring the number of planets from eight to the sacred number nine, there would be at least ten and maybe 12 "planets".

But on the other hand Pluto defied expectation in other ways that argue for it being a planet. Like you said -it is a geologically active world. Perhaps second only to earth in having stuff going on on its surface.

Also it has four moons of its own. Earth is actually a bit of freak compared to the other 8 currently recognized planets because it has moon much bigger relative to its size than any other. Mars has two moons, but one is about the size of Mount Everest, and the other about the size of Mount Shasta. Tiny.

Jupiter, Saturn, and Neptune, each have more, and bigger moons, than Earth. And Uranus has a moon about half as wide as the earth's moon - on top of having 27 other moons. But all four of these planets are gas giants FAR bigger than earth (more like the small cold versions of the Sun).

But Earth's Moon is a quarter as wide, and one 80th the mass of earth. More like a "binary planet system" than a typical "earth-moon" set up.

However we now know that Pluto (smaller than our moon) has its own moon Charon that is only slightly smaller than itself. Almost equal in size. And that Pluto has three other moons.

So pluto is freakier than the earth-moon system, and Pluto has a bigger entourage of moons retative to its small size than any other planet known so far.



RubyWings91
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19 Feb 2020, 10:23 am

I currently feel that Pluto classifies as a planet, since I feel like any large object with enough gravity to take on the shape of a sphere that revolves around the sun but not a around a planet should also be considered a planet. Of course, several other objects would classify as planets under this definition but I see no problem in there being more than 9 planets, personally. Convenience should never be an argument from exclusion. We all know that we have over two hundred bones in the human body but most people don't need to be able to name them all, I personally see nothing wrong with their being a couple dozen planets and most people only knowing the largest few among them.

I think the scientists should either set up a definition of a planet that isn't so vague as our current one or a separate planet class for these smaller objects. Either would help solve this problem. Until the clarity is addressed, I think this will always be a debate.



naturalplastic
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19 Feb 2020, 10:50 pm

Ceres is an asteroid. Not a transneptunian "dirty snowball" in the cold outer solar system, but a big rock smack in the middle of the asteroid belt between Mars and Jupiter. It has an enough mass for gravity to form it into a round sphere. And it doesn't revolve around a planet but has its own orbit around the sun.

But...its only 480 miles wide (less than a quarter as wide as our moon).

If you are willing promote something that tiny to the status of "planet" then we could go with that definition I suppose. And reinstate Pluto to its former glory. But a lot of other ….cosmic riff-raff, would also have to be so promoted. But if you can live with double digit numbers of "planets" then maybe that's ok. Lol!

Yes the concept of "planet" is fuzzy, and has already morphed over the ages. The word "planet" comes from the ancient Greek word for "wanderer". The ancients saw that there were two kinds of lights in the sky: those little things that don't move (the "fixed" stars)and the large and small things that do move(the moon, sun, and five points of light that look like stars but move (Mercury, Venus, Mars, Jupiter, and Saturn). So the sun, moon, and those five other things were all dubbed "planets". Earth was NOT a planet.

It wasn't until Galileo and telescopes that we realized that the earth went around the sun, that the sun was a star, and that other planets had moons.

So earth got downgraded to just being a planet. The Sun got promoted to higher rank than a planet. And the moon got demoted to below being a planet, into being "a moon" (with the newly discovered moons of other planets it was now in this newly created lower paygrade).

Then they discovered asteroids/planetoids, and comets. Planet like but too small to be planets. Then they discovered Uranus, Neptune, and finally Pluto. In some ways Pluto is more like a comet than like the earth. But in some ways the four gas giants (Uranus, Neptune, Saturn, and Jupiter) are more like the Sun and the stars than like the earth. So "planet" already does cover some rather unlike objects.



cosine
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01 Mar 2020, 12:33 am

the definition i've always used in years past is:

one: orbits the sun directly by being at least half as massive as any partner it orbits with. this allows a pair of planets that orbit around each other but are not exactly the same size.

two: big enough to be within 5% of being spherical.

if we have "minor planets" do we also have "major planets" :?:



naturalplastic
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01 Mar 2020, 7:16 pm

cosine wrote:
the definition i've always used in years past is:

one: orbits the sun directly by being at least half as massive as any partner it orbits with. this allows a pair of planets that orbit around each other but are not exactly the same size.

two: big enough to be within 5% of being spherical.

if we have "minor planets" do we also have "major planets" :?:


We have normal "planets", and "dwarf planets" (aka 'minor planets').

But actually the normal "planets" actually include two very different types of bodies. The smaller solid surfaced "terrestrial planets"( Earth,Mecury, Venus, Mars), and the larger "gas giants"(Neptune, Uranus, Saturn, Jupiter).

So the category of "planet" really should be subdivided into two species. With the Gas Giants being called "Giant planets".And the others being simply "planets".



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02 Mar 2020, 9:14 am

Once we're done with arguing over whether or not Pluto deserves to be called a planet, we can move on to more important matters; like how many angels can dance on the head of a pin, who is buried in Grant's tomb, the price of tea in China, and whether or not Han shot first.

:wink:


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Tanner7
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03 Mar 2020, 9:25 pm

The Titius-Bode Rule is a relationship between the semimajor axes (orbit radius) of planets. It works for all planets except Neptune. Interestingly, Pluto's semimajor axis is where Neptune's should be by the Titius-Bode Rule, even though Pluto's orbit is way off the ecliptic and Pluto is nothing like the gas giants. https://en.wikipedia.org/wiki/Titius%E2%80%93Bode_law
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04 Mar 2020, 9:04 am

Tanner7 wrote:
The Titius-Bode Rule ...
... has been thoroughly debunked.

The "Titius-Bode Hypothesis" was once used to predict the spacing between the planets in our solar system. (It is basically a simple reiterative numerical formula). German astronomer Johann Daniel Titius was the first to create the empirical rule, which seemed to reliably predict the distances of each planet from the Sun. In fact, the law even proposed the existence of an unseen planet between Mars and Jupiter, which turned out to be the asteroid belt.

At the time of Titius's idea -- 1766 to be exact -- Uranus, Neptune and Pluto were as yet unobserved. Shortly after the hypothesis was unveiled to the public, a fellow German named Johann Elert Bode took ownership of it, popularizing it much further, especially after it was proven to work with Uranus’s orbit (The planet was documented in 1781).

However, in 1846, upon observation of the planet Neptune, "Bode’s Law" was proven to be nothing more than a mere coincidence, a numerical curiosity of nature. Even more significant, Bode's Law does not apply to extra-solar planetary systems.

Welcome to the 21st century.


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cosine
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04 Mar 2020, 8:32 pm

nature is what it is. call things what you like; nature does not care and will not hear you.

calling things whatever is about communication. if your friend calls it a "round rock" then you can call it that, too, and communicate with your friend.

is there more difference between (one of mercury, venus, earth, mars) and pluto or between (one of mercury, venus, earth, mars) and (one of jupiter, saturn, uranus, neptune)? does difference matter? this would depend on the importance of each of the many differences that do exist.



naturalplastic
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05 Apr 2020, 4:53 pm

cosine wrote:
the definition i've always used in years past is:

one: orbits the sun directly by being at least half as massive as any partner it orbits with. this allows a pair of planets that orbit around each other but are not exactly the same size.

two: big enough to be within 5% of being spherical.

:


Makes sense. A spherical body that orbits directly around the star. But can be co-equal with a partner as a "double planet" if the two bodies are similar in mass and the center of rotation about each other is between the two in space.

Pluto would then count as a planet. And maybe its partner Charon would be promoted to planet status as well, with pluto and Charon being classed as a "bianary planet" so to speak. Not sure what the mass ratio between them is but I do know Charon is close to Pluto's size.