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 Post subject: Redefinition of Planet
PostPosted: Mon Feb 20, 2017 8:18 am 
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NASA Scientists Have Proposed a New Definition of Planets, and Pluto Could Soon Be Back

http://www.sciencealert.com/nasa-scient ... everything

Quote:
"A planet is a sub-stellar mass body that has never undergone nuclear fusion and that has sufficient self-gravitation to assume a spheroidal shape adequately described by a triaxial ellipsoid regardless of its orbital parameters."


OTOH, this plays into my theory that Batygin and Brown are keeping mum 'til Planet Nine is confirmed either behind the scenes or with the new crowdsourced Planet Nine search.

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PostPosted: Tue Feb 21, 2017 1:04 pm 
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What on earth is a triaxial ellipsoid? I own dozens of astronomy books with information on planets and this term never appears. Does this mean that all these books are now officially out-of-date and should be banned?

Would this NASA-created definition include all spherical asteroids?
Personally, I would like a definition of planet that does not include asteroids. Personally.

To me a planet is a spherical object that goes around the Sun, is not a comet or asteroid, and can be seen with at least some portable amateur telescopes. This would include Pluto. Same old nine planets. Let's leave it at that.

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PostPosted: Tue Feb 21, 2017 6:18 pm 
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doctorcos wrote:
What on earth is a triaxial ellipsoid?


Try Wikipedia next time.

https://en.wikipedia.org/wiki/Ellipsoid

They use "tri-axial" rather than triaxial" so a simple word search will help in understanding this term.

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PostPosted: Thu Feb 23, 2017 1:37 pm 
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From Webster's 1913 dictionary ( http://www.webster-dictionary.org/definition/planet )

Planet: A celestial body which revolves about the sun in an orbit of a moderate degree of eccentricity. It is distinguished from a comet by the absence of a coma, and by having a less eccentric orbit.

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PostPosted: Wed Mar 29, 2017 7:53 am 
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I believe this article by Jason Wright is relevant to a previous link about the redefinition of a planet.

Astronomy and “Meta-Astronomy”: An Allegory

http://sites.psu.edu/astrowright/2017/0 ... -allegory/

Astronomers aren't authorities on geology, and geologists aren't authorities on astronomy. Neither side, or at least in this case astronomers, don't want to hear a geologist's argument for an object being a planet. Yet if both sides converse and collaborate, they could come to a consensus with an emphasis upon science rather than opinion and shaky sub-definitions. i.e. Clearing the orbital path.

And a fun little opinion piece.

Ringo Is a Beatle, Hawaii Is a State—Why Isn’t Pluto a Planet?

https://www.scientificamerican.com/arti ... -a-planet/

Quote:
After more than a decade of controversy, the debate over the icy world’s demotion to “dwarf planet” status shows no sign of stopping.

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PostPosted: Wed Mar 29, 2017 7:04 pm 
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There is and never was enough justification to remove Pluto as a planet. In my opinion, this was just a power play by the IAU and grandstanding by a certain scientist to get publicity for his work.

Maybe 50 years from now, we'll know more about astronomy and the languages of the world will naturally gravitate to definitions of planet (or its equivalent in other languages) that make sense scientifically as well as facilitate communication.

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PostPosted: Thu Mar 30, 2017 10:41 am 
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Matthew

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PostPosted: Wed May 30, 2018 8:10 pm 
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Here we go again. The following article indicates that Pluto may be a comet. Will this cause the bureaucrats at the IAU to meddle with the definitions of planet, dwarf planet, comet, plutoid, and tran-Neptunian object?

https://www.msn.com/en-us/news/technolo ... smsnnews11

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