The search for Planet 9

Discuss our solar system.
User avatar
Graeme1858 Great Britain
Co-Administrator
Co-Administrator
Articles: 1
Online
Posts: 7217
Joined: Mon Jun 24, 2019 7:16 pm
4
Location: North Kent, UK
Status:
Online

TSS Awards Badges

TSS Photo of the Day

I Broke The Forum.

Re: The search for Planet 9

#21

Post by Graeme1858 »


Bigzmey wrote: Fri Aug 27, 2021 3:42 pm
KingNothing13 wrote: Fri Aug 27, 2021 12:08 pm :popcorn:

I didn't mean to stir up a hornet's nest......
Not a hornet's nest (I hope). Just civilized discussion among friends. :)

definitely not a hornet's nest! We all hold opinions, some strongly, some we're not so fussed about. nFA will always back science to the hilt and we all respect him for it. But he can't help being wrong sometimes! :lol:

Sorry your thread was pirated Brett! The OP was indeed an interesting article.

Regards

Graeme
______________________________________________
Celestron 9.25 f10 SCT, f6.3FR, CGX mount.
ASI1600MM Pro, ASI294MC Pro, ASI224MC
ZWO EFW, ZWO OAG, ASI220MM Mini.
APM 11x70 ED APO Binoculars.

https://www.averywayobservatory.co.uk/
User avatar
Lady Fraktor Slovakia
Co-Administrator
Co-Administrator
Articles: 0
Offline
Posts: 9860
Joined: Mon Apr 29, 2019 9:14 pm
4
Location: Slovakia
Status:
Offline

Re: The search for Planet 9

#22

Post by Lady Fraktor »


To your original posting Brent, I used to listen to Phil Plait Bad Astronomy podcast quite often in the past.
Always entertaining and he is a good presenter.
See Far Sticks: Antares Elita 103/1575, AOM FLT 105/1000, Bresser BV 127/1200, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS100/1000, Vixen SD115s/885
EQ: TAL MT-1, Vixen SXP, AXJ, AXD
Az/Alt: AYO Digi II/ Argo Navis, Stellarvue M2C/ Argo Navis
Tripods: Berlebach Planet (2), Uni 28 Astro, Report 372, TAL factory maple, Vixen ASG-CB90, Vixen AXD-TR102
Diagonals: Astro-Physics, Baader Amici, Baader Herschel, iStar Blue, Stellarvue DX, Takahashi prism, TAL, Vixen flip mirror
Eyepieces: Antares to Zeiss
The only culture I have is from yogurt
My day was going well until... people
Image
User avatar
KingNothing13 United States of America
Moderator
Moderator
Articles: 0
Online
Posts: 1712
Joined: Wed Jun 19, 2019 4:54 pm
4
Location: Western Mass
Status:
Online

TSS Awards Badges

Re: The search for Planet 9

#23

Post by KingNothing13 »


Perhaps "Hornet's Nest" was a poor "turn of phrase" so to speak :) I know there's no animosity in this thread, and it is entertaining.
-- Brett

Scope: Apertura AD10 with Nexus II with 8192/716000 Step Encoders
EPs: ES 82* 18mm, 11mm, 6.7mm; GSO 30mm
Celestron SkyMaster 15x70 Binoculars
List Counts: Messier: 75; Herschel 400: 30; Caldwell: 12; AL Carbon Star List: 16
Brett's Carbon Star Hunt

Image
User avatar
notFritzArgelander
In Memory
In Memory
Articles: 0
Offline
Posts: 14925
Joined: Fri May 10, 2019 4:13 pm
4
Location: Idaho US
Status:
Offline

TSS Awards Badges

Re: The search for Planet 9

#24

Post by notFritzArgelander »


Graeme1858 wrote: Fri Aug 27, 2021 11:19 am Well we could argue all day. We agree on some points but not others. But this one is not clear cut with respect to science and logic. It is much more subjective. I agree with both points of your last paragraph.

For you (and most) it's important that it was wrong to change the classification of Pluto for whatever reason. For me it's just names and not so important. What's important for me (and most) is that Pluto is an object which exceeds expectations for interest, curiosity and beauty.


Regards

Graeme
Oh I agree that Nature doesn't care what names we call it. However the names we construct for things should at least be clearly defined and free of self contradiction. The IAUs adopted definition is not clear and is self contradictory. For instance there is no criterion for clearing an orbit. Earth, Mars, Jupiter and Neptune have not fully cleared their orbits any more than Pluto, Ceres, Eris and Sedna. So should Earth, Mars, Jupiter and Neptune be excluded as planets? Lack of clarity leads to self contradiction.

There is no hornets nest AFAIK. However many folks are profoundly disappointed by the political aspects of the IAUs redefinition. I for one am profoundly chagrined at the way the IAU process foisted a bad definition on us all. It would have been better to leave planet undefined! I am profoundly disappointed that folks I fully expect to "know better" should commit such an atrocious attempt at a definition. That's the nub of it. Folks with less deep a connection to science and scientific principles care less deeply. So it goes.

For instance from https://en.wikipedia.org/wiki/IAU_definition_of_planet
In an 18 August 2006 Science Friday interview, Mike Brown expressed doubt that a scientific definition was even necessary. He stated, "The analogy that I always like to use is the word "continent". You know, the word "continent" has no scientific definition ... they're just cultural definitions, and I think the geologists are wise to leave that one alone and not try to redefine things so that the word "continent" has a big, strict definition."[28]
Scopes: Refs: Orion ST80, SV 80EDA f7, TS 102ED f11 Newts: AWB 130mm, f5, Z12 f5; Cats: VMC110L, Intes MK66,VMC200L f9.75 EPs: KK Fujiyama Orthoscopics, 2x Vixen NPLs (40-6mm) and BCOs, Baader Mark IV zooms, TV Panoptics, Delos, Plossl 32-8mm. Mixed brand Masuyama/Astroplans Binoculars: Nikon Aculon 10x50, Celestron 15x70, Baader Maxbright. Mounts: Star Seeker IV, Vixen Porta II, Celestron CG5
User avatar
KingNothing13 United States of America
Moderator
Moderator
Articles: 0
Online
Posts: 1712
Joined: Wed Jun 19, 2019 4:54 pm
4
Location: Western Mass
Status:
Online

TSS Awards Badges

Re: The search for Planet 9

#25

Post by KingNothing13 »


And a little more about the definition of planet, since we've turned in that direction. :lol:

https://www.sciencenews.org/article/plu ... n-demotion
-- Brett

Scope: Apertura AD10 with Nexus II with 8192/716000 Step Encoders
EPs: ES 82* 18mm, 11mm, 6.7mm; GSO 30mm
Celestron SkyMaster 15x70 Binoculars
List Counts: Messier: 75; Herschel 400: 30; Caldwell: 12; AL Carbon Star List: 16
Brett's Carbon Star Hunt

Image
User avatar
Bigzmey United States of America
Moderator
Moderator
Articles: 8
Offline
Posts: 7548
Joined: Sat May 11, 2019 7:55 pm
4
Location: San Diego, CA USA
Status:
Offline

TSS Awards Badges

Re: The search for Planet 9

#26

Post by Bigzmey »


KingNothing13 wrote: Sat Aug 28, 2021 4:12 pm And a little more about the definition of planet, since we've turned in that direction. :lol:

https://www.sciencenews.org/article/plu ... n-demotion
Good story.
Scopes: Stellarvue: SV102ED; Celestron: 9.25" EdgeHD, 8" SCT, 150ST, Onyx 80ED; iOptron: Hankmeister 6" Mak; SW: 7" Mak; Meade: 80ST.
Mounts: SW: SkyTee2, AzGTi; iOptron: AZMP; ES: Twilight I; Bresser: EXOS2; UA: MicroStar.
Binos: APM: 100-90 APO; Canon: IS 15x50; Orion: Binoviewer, LG II 15x70, WV 10x50, Nikon: AE 16x50, 10x50, 8x40.
EPs: Pentax: XWs & XFs; TeleVue: Delites, Panoptic & Plossls; ES: 68, 62; Vixen: SLVs; Baader: BCOs, Aspherics, Mark IV.
Diagonals: Baader: BBHS mirror, Zeiss Spec T2 prism, Clicklock dielectric; TeleVue: Evebrite dielectric; AltairAstro: 2" prism.
Filters: Lumicon: DeepSky, UHC, OIII, H-beta; Baader: Moon & SkyGlow, Contrast Booster, UHC-S, 6-color set; Astronomik: UHC.

Observing: DSOs: 3106 (Completed: Messier, Herschel 1, 2, 3. In progress: H2,500: 2180, S110: 77). Doubles: 2382, Comets: 34, Asteroids: 255
User avatar
notFritzArgelander
In Memory
In Memory
Articles: 0
Offline
Posts: 14925
Joined: Fri May 10, 2019 4:13 pm
4
Location: Idaho US
Status:
Offline

TSS Awards Badges

Re: The search for Planet 9

#27

Post by notFritzArgelander »


KingNothing13 wrote: Sat Aug 28, 2021 4:12 pm And a little more about the definition of planet, since we've turned in that direction. :lol:

https://www.sciencenews.org/article/plu ... n-demotion
But let us bring it back specifically to Beelzebrown's alleged "Planet 9" and link it to the IAU's definition. Does it satisfy the IAU definition?

NO! :lol: It hasn't cleared it orbit! The illustration in the OP's link shows 6 (yes, count 'em SIX!) known TNOs that cross its orbit. So it, if it exists, has merely anti correlated the orbits of crossing bodies! It has not "cleared its neighborhood"!

The fact that the folks who search for "Planet 9" call it a planet in contradiction of the very definition of planet they have adopted shows that the IAU definition is incoherent, leads to self contradictions and confusions and that the orbit clearing criterion is problematic.

Let the number of planets grow, defined only by geophysical properties since orbital characteristics are demonstrably irrelevant.

And as for the remark of @Graeme1858
nFA will always back science to the hilt and we all respect him for it. But he can't help being wrong sometimes! :lol:
It is true that I cannot help being wrong sometimes. I am human. But since it has been demonstrated that the IAU definition leads to self contradictions, and leading to contradictions and falsifications by data is bad science, the IAU definition is most definitely bad science. I'm not wrong about that.

I'll admit to being wrong only upon being shown data or logic. Being declared wrong by a purported authority just won't cut it. :)
Scopes: Refs: Orion ST80, SV 80EDA f7, TS 102ED f11 Newts: AWB 130mm, f5, Z12 f5; Cats: VMC110L, Intes MK66,VMC200L f9.75 EPs: KK Fujiyama Orthoscopics, 2x Vixen NPLs (40-6mm) and BCOs, Baader Mark IV zooms, TV Panoptics, Delos, Plossl 32-8mm. Mixed brand Masuyama/Astroplans Binoculars: Nikon Aculon 10x50, Celestron 15x70, Baader Maxbright. Mounts: Star Seeker IV, Vixen Porta II, Celestron CG5
User avatar
KingNothing13 United States of America
Moderator
Moderator
Articles: 0
Online
Posts: 1712
Joined: Wed Jun 19, 2019 4:54 pm
4
Location: Western Mass
Status:
Online

TSS Awards Badges

Re: The search for Planet 9

#28

Post by KingNothing13 »


notFritzArgelander wrote: Sat Aug 28, 2021 10:20 pm

Let the number of planets grow, defined only by geophysical properties since orbital characteristics are demonstrably irrelevant.


I'll admit to being wrong only upon being shown data or logic. Being declared wrong by a purported authority just won't cut it. :)
I agree with both of these points.

What would you call it a hunt for, nFA, if anything? The science *seems* to support *something* out there. But I could be wrong, and usually am. :lol:
-- Brett

Scope: Apertura AD10 with Nexus II with 8192/716000 Step Encoders
EPs: ES 82* 18mm, 11mm, 6.7mm; GSO 30mm
Celestron SkyMaster 15x70 Binoculars
List Counts: Messier: 75; Herschel 400: 30; Caldwell: 12; AL Carbon Star List: 16
Brett's Carbon Star Hunt

Image
User avatar
notFritzArgelander
In Memory
In Memory
Articles: 0
Offline
Posts: 14925
Joined: Fri May 10, 2019 4:13 pm
4
Location: Idaho US
Status:
Offline

TSS Awards Badges

Re: The search for Planet 9

#29

Post by notFritzArgelander »


KingNothing13 wrote: Sat Aug 28, 2021 11:11 pm
notFritzArgelander wrote: Sat Aug 28, 2021 10:20 pm

Let the number of planets grow, defined only by geophysical properties since orbital characteristics are demonstrably irrelevant.


I'll admit to being wrong only upon being shown data or logic. Being declared wrong by a purported authority just won't cut it. :)
I agree with both of these points.

What would you call it a hunt for, nFA, if anything? The science *seems* to support *something* out there. But I could be wrong, and usually am. :lol:
It depends on whether you are highly selective about your reading. :)

There is an older thread on astrophysics that casts doubt assume that the object that is causing any orbital clustering. The alleged clustering could be simply observational bias in the observations of TNOs. Based on where on Earth these searches are being done from you'd expect that there would be bias in the observed orbits. Here is the thread:

https://phys.org/news/2021-02-evidence- ... ering.html

https://www.livescience.com/planet-9-doubts.html

And even if you believe in the clustering of TNO orbits, there is no reason to assuming that it is due to an object that is still there! A passing rogue planet could do the same trick if it is real. Simulations show that IF the the correlations in TNO orbits holds up after repeated observations with better all sky coverage that there is a 60% chance that a passing rogue could do the trick and only a 40% chance it would be captured.

The evidence as to whether there is an an object is there to be found is far from conclusive.

No Evidence for Orbital Clustering in the Extreme Trans-Neptunian Objects

https://arxiv.org/abs/2102.05601
The apparent clustering in longitude of perihelion ϖ and ascending node Ω of extreme trans-Neptunian objects (ETNOs) has been attributed to the gravitational effects of an unseen 5-10 Earth-mass planet in the outer solar system. To investigate how selection bias may contribute to this clustering, we consider 14 ETNOs discovered by the Dark Energy Survey, the Outer Solar System Origins Survey, and the survey of Sheppard and Trujillo. Using each survey's published pointing history, depth, and TNO tracking selections, we calculate the joint probability that these objects are consistent with an underlying parent population with uniform distributions in ϖ and Ω. We find that the mean scaled longitude of perihelion and orbital poles of the detected ETNOs are consistent with a uniform population at a level between 17% and 94%, and thus conclude that this sample provides no evidence for angular clustering.
So far the composition of alleged Planet 9 is mostly hot air?
Last edited by notFritzArgelander on Sun Aug 29, 2021 12:27 am, edited 1 time in total.
Scopes: Refs: Orion ST80, SV 80EDA f7, TS 102ED f11 Newts: AWB 130mm, f5, Z12 f5; Cats: VMC110L, Intes MK66,VMC200L f9.75 EPs: KK Fujiyama Orthoscopics, 2x Vixen NPLs (40-6mm) and BCOs, Baader Mark IV zooms, TV Panoptics, Delos, Plossl 32-8mm. Mixed brand Masuyama/Astroplans Binoculars: Nikon Aculon 10x50, Celestron 15x70, Baader Maxbright. Mounts: Star Seeker IV, Vixen Porta II, Celestron CG5
User avatar
KingNothing13 United States of America
Moderator
Moderator
Articles: 0
Online
Posts: 1712
Joined: Wed Jun 19, 2019 4:54 pm
4
Location: Western Mass
Status:
Online

TSS Awards Badges

Re: The search for Planet 9

#30

Post by KingNothing13 »


Thanks nFA - I will try to check those out in the next couple of days.

I should check out the astrophysics forum more often - but most of the time it is WAY above my head, but can't learn without looking.
-- Brett

Scope: Apertura AD10 with Nexus II with 8192/716000 Step Encoders
EPs: ES 82* 18mm, 11mm, 6.7mm; GSO 30mm
Celestron SkyMaster 15x70 Binoculars
List Counts: Messier: 75; Herschel 400: 30; Caldwell: 12; AL Carbon Star List: 16
Brett's Carbon Star Hunt

Image
User avatar
notFritzArgelander
In Memory
In Memory
Articles: 0
Offline
Posts: 14925
Joined: Fri May 10, 2019 4:13 pm
4
Location: Idaho US
Status:
Offline

TSS Awards Badges

Re: The search for Planet 9

#31

Post by notFritzArgelander »


KingNothing13 wrote: Sun Aug 29, 2021 12:17 am Thanks nFA - I will try to check those out in the next couple of days.

I should check out the astrophysics forum more often - but most of the time it is WAY above my head, but can't learn without looking.
Sorry to hear that the astrophysics forum is problematic. I try to answer questions to clarify sticky points. It is very hard for me to guess in advance what the issues might be.

The main thing to keep in mind when reading those links is that TNOs have been searched for from a small number of locations and there is no "all sky" survey for TNOs. So the "observed correlation" in TNO orbit is just what you would expect from selectively sampling a distribution that was actually even and unclustered.

The whole Planet 9 thing is overly hyped on the basis of a biased sample.

Mike Brown (aka Beelzebrown thanks to @Lady Fraktor ) has been obsessed with "finding a planet". The whole campaign to demote Pluto started when he found Eris (he originally named it Xenia) and since it was larger than Pluto he and NASA started referring to it as a 10th planet. When the IAU balked at this, (out of pique?) he started a campaign to eliminate Pluto.

So the whole motivation behind the IAU pseudo-definition is IMO corrupt. We should accept Nature as is and leave our desires (to have a short list of planets, our chagrin at being denied being the discovery of a planet) aside.
Scopes: Refs: Orion ST80, SV 80EDA f7, TS 102ED f11 Newts: AWB 130mm, f5, Z12 f5; Cats: VMC110L, Intes MK66,VMC200L f9.75 EPs: KK Fujiyama Orthoscopics, 2x Vixen NPLs (40-6mm) and BCOs, Baader Mark IV zooms, TV Panoptics, Delos, Plossl 32-8mm. Mixed brand Masuyama/Astroplans Binoculars: Nikon Aculon 10x50, Celestron 15x70, Baader Maxbright. Mounts: Star Seeker IV, Vixen Porta II, Celestron CG5
User avatar
notFritzArgelander
In Memory
In Memory
Articles: 0
Offline
Posts: 14925
Joined: Fri May 10, 2019 4:13 pm
4
Location: Idaho US
Status:
Offline

TSS Awards Badges

Re: The search for Planet 9

#32

Post by notFritzArgelander »


NASA's APOD for today is relevant.

https://apod.nasa.gov/apod/astropix.html

How can you look at a plot like that and claim Mercury, Venus, Earth, and Mars have cleared their orbits? :lol:
Scopes: Refs: Orion ST80, SV 80EDA f7, TS 102ED f11 Newts: AWB 130mm, f5, Z12 f5; Cats: VMC110L, Intes MK66,VMC200L f9.75 EPs: KK Fujiyama Orthoscopics, 2x Vixen NPLs (40-6mm) and BCOs, Baader Mark IV zooms, TV Panoptics, Delos, Plossl 32-8mm. Mixed brand Masuyama/Astroplans Binoculars: Nikon Aculon 10x50, Celestron 15x70, Baader Maxbright. Mounts: Star Seeker IV, Vixen Porta II, Celestron CG5
User avatar
KingNothing13 United States of America
Moderator
Moderator
Articles: 0
Online
Posts: 1712
Joined: Wed Jun 19, 2019 4:54 pm
4
Location: Western Mass
Status:
Online

TSS Awards Badges

Re: The search for Planet 9

#33

Post by KingNothing13 »


notFritzArgelander wrote: Sun Aug 29, 2021 5:26 am NASA's APOD for today is relevant.

https://apod.nasa.gov/apod/astropix.html

How can you look at a plot like that and claim Mercury, Venus, Earth, and Mars have cleared their orbits? :lol:
That's a great picture! Thanks for posting that.

But if we don't meed their definition for a planet, what the heck are we living on? :lol:
-- Brett

Scope: Apertura AD10 with Nexus II with 8192/716000 Step Encoders
EPs: ES 82* 18mm, 11mm, 6.7mm; GSO 30mm
Celestron SkyMaster 15x70 Binoculars
List Counts: Messier: 75; Herschel 400: 30; Caldwell: 12; AL Carbon Star List: 16
Brett's Carbon Star Hunt

Image
User avatar
MistrBadgr United States of America
Orion Spur Ambassador
Articles: 0
Offline
Posts: 748
Joined: Sat May 11, 2019 9:27 pm
4
Location: Broken Arrow, Okla, USA
Status:
Offline

TSS Awards Badges

Re: The search for Planet 9

#34

Post by MistrBadgr »


The big question in my mind is, "What objects have a closest approach to Pluto that is the same or less than the closest approach of Venus and the Earth, that keep it from having a clear path?" Seems to me, if Pluto does not have something like that, then how do we justify Earth and Venus being planets?
Bill Steen
Many small scopes, plus a Lightbridge 12, LX 70-8R,6R,6M
Many eyepieces, just not really expensive ones.
User avatar
notFritzArgelander
In Memory
In Memory
Articles: 0
Offline
Posts: 14925
Joined: Fri May 10, 2019 4:13 pm
4
Location: Idaho US
Status:
Offline

TSS Awards Badges

Re: The search for Planet 9

#35

Post by notFritzArgelander »


KingNothing13 wrote: Sun Aug 29, 2021 1:02 pm
notFritzArgelander wrote: Sun Aug 29, 2021 5:26 am NASA's APOD for today is relevant.

https://apod.nasa.gov/apod/astropix.html

How can you look at a plot like that and claim Mercury, Venus, Earth, and Mars have cleared their orbits? :lol:
That's a great picture! Thanks for posting that.

But if we don't meed their definition for a planet, what the heck are we living on? :lol:
Well, it certainly demonstrates that the IAU definition is completely inadequate. :)
Scopes: Refs: Orion ST80, SV 80EDA f7, TS 102ED f11 Newts: AWB 130mm, f5, Z12 f5; Cats: VMC110L, Intes MK66,VMC200L f9.75 EPs: KK Fujiyama Orthoscopics, 2x Vixen NPLs (40-6mm) and BCOs, Baader Mark IV zooms, TV Panoptics, Delos, Plossl 32-8mm. Mixed brand Masuyama/Astroplans Binoculars: Nikon Aculon 10x50, Celestron 15x70, Baader Maxbright. Mounts: Star Seeker IV, Vixen Porta II, Celestron CG5
User avatar
notFritzArgelander
In Memory
In Memory
Articles: 0
Offline
Posts: 14925
Joined: Fri May 10, 2019 4:13 pm
4
Location: Idaho US
Status:
Offline

TSS Awards Badges

Re: The search for Planet 9

#36

Post by notFritzArgelander »


MistrBadgr wrote: Sun Aug 29, 2021 4:18 pm The big question in my mind is, "What objects have a closest approach to Pluto that is the same or less than the closest approach of Venus and the Earth, that keep it from having a clear path?" Seems to me, if Pluto does not have something like that, then how do we justify Earth and Venus being planets?
The IAU redefinition of a planet is hopeless scientifically because it has no criterion for clearing a path. There are several proposals for making sense of being gravitationally dominant in its orbit. If there is interest I can post about it maybe on astrophysics because there is math involved. But basically the difference is that these proposals have a quantitative criterion for what gravitational dominance means in an orbit. If the IAU would have a criterion that is measurable in its definition I would be a less disappointed, But I would still prefer that the definition be based on the properties of the object itself not the chaotic accidents of orbits. Does a rogue planet cease to be a planet once it's gone rogue?

For example, orbital analyses indicate that the Solar System ejected a fifth giant planet billions of years ago. Is that planet no longer a planet because Jupiter kicked it out of the Solar System? I think that's silly. It's another pointer that "orbit clearing" should be irrelevant in any proposed scientific definition of a planet.

https://www.scientificamerican.com/arti ... st-planet/
Scopes: Refs: Orion ST80, SV 80EDA f7, TS 102ED f11 Newts: AWB 130mm, f5, Z12 f5; Cats: VMC110L, Intes MK66,VMC200L f9.75 EPs: KK Fujiyama Orthoscopics, 2x Vixen NPLs (40-6mm) and BCOs, Baader Mark IV zooms, TV Panoptics, Delos, Plossl 32-8mm. Mixed brand Masuyama/Astroplans Binoculars: Nikon Aculon 10x50, Celestron 15x70, Baader Maxbright. Mounts: Star Seeker IV, Vixen Porta II, Celestron CG5
User avatar
notFritzArgelander
In Memory
In Memory
Articles: 0
Offline
Posts: 14925
Joined: Fri May 10, 2019 4:13 pm
4
Location: Idaho US
Status:
Offline

TSS Awards Badges

Re: The search for Planet 9

#37

Post by notFritzArgelander »


notFritzArgelander wrote: Sun Aug 29, 2021 5:40 pm
MistrBadgr wrote: Sun Aug 29, 2021 4:18 pm The big question in my mind is, "What objects have a closest approach to Pluto that is the same or less than the closest approach of Venus and the Earth, that keep it from having a clear path?" Seems to me, if Pluto does not have something like that, then how do we justify Earth and Venus being planets?
The IAU redefinition of a planet is hopeless scientifically because it has no criterion for clearing a path. There are several proposals for making sense of being gravitationally dominant in its orbit. If there is interest I can post about it maybe on astrophysics because there is math involved. But basically the difference is that these proposals have a quantitative criterion for what gravitational dominance means in an orbit. If the IAU would have a criterion that is measurable in its definition I would be a less disappointed, But I would still prefer that the definition be based on the properties of the object itself not the chaotic accidents of orbits. Does a rogue planet cease to be a planet once it's gone rogue?

For example, orbital analyses indicate that the Solar System ejected a fifth giant planet billions of years ago. Is that planet no longer a planet because Jupiter kicked it out of the Solar System? I think that's silly. It's another pointer that "orbit clearing" should be irrelevant in any proposed scientific definition of a planet.

https://www.scientificamerican.com/arti ... st-planet/
PS Neptune can't be a planet because it hasn't cleared its orbit of Pluto. :)
Scopes: Refs: Orion ST80, SV 80EDA f7, TS 102ED f11 Newts: AWB 130mm, f5, Z12 f5; Cats: VMC110L, Intes MK66,VMC200L f9.75 EPs: KK Fujiyama Orthoscopics, 2x Vixen NPLs (40-6mm) and BCOs, Baader Mark IV zooms, TV Panoptics, Delos, Plossl 32-8mm. Mixed brand Masuyama/Astroplans Binoculars: Nikon Aculon 10x50, Celestron 15x70, Baader Maxbright. Mounts: Star Seeker IV, Vixen Porta II, Celestron CG5
User avatar
notFritzArgelander
In Memory
In Memory
Articles: 0
Offline
Posts: 14925
Joined: Fri May 10, 2019 4:13 pm
4
Location: Idaho US
Status:
Offline

TSS Awards Badges

Re: The search for Planet 9

#38

Post by notFritzArgelander »


I've started this thread on preferring "gravitational dominance" to "clearing the neighborhood" for classifying different types of planets.

viewtopic.php?f=74&t=20186
Scopes: Refs: Orion ST80, SV 80EDA f7, TS 102ED f11 Newts: AWB 130mm, f5, Z12 f5; Cats: VMC110L, Intes MK66,VMC200L f9.75 EPs: KK Fujiyama Orthoscopics, 2x Vixen NPLs (40-6mm) and BCOs, Baader Mark IV zooms, TV Panoptics, Delos, Plossl 32-8mm. Mixed brand Masuyama/Astroplans Binoculars: Nikon Aculon 10x50, Celestron 15x70, Baader Maxbright. Mounts: Star Seeker IV, Vixen Porta II, Celestron CG5
User avatar
notFritzArgelander
In Memory
In Memory
Articles: 0
Offline
Posts: 14925
Joined: Fri May 10, 2019 4:13 pm
4
Location: Idaho US
Status:
Offline

TSS Awards Badges

Re: The search for Planet 9

#39

Post by notFritzArgelander »


phys.org had this relatively balanced article that covers the topic in the OP.

https://phys.org/news/2021-08-planet.html
Scopes: Refs: Orion ST80, SV 80EDA f7, TS 102ED f11 Newts: AWB 130mm, f5, Z12 f5; Cats: VMC110L, Intes MK66,VMC200L f9.75 EPs: KK Fujiyama Orthoscopics, 2x Vixen NPLs (40-6mm) and BCOs, Baader Mark IV zooms, TV Panoptics, Delos, Plossl 32-8mm. Mixed brand Masuyama/Astroplans Binoculars: Nikon Aculon 10x50, Celestron 15x70, Baader Maxbright. Mounts: Star Seeker IV, Vixen Porta II, Celestron CG5
User avatar
AntennaGuy United States of America
Milky Way Ambassador
Articles: 0
Offline
Posts: 1409
Joined: Sun May 19, 2019 1:20 am
4
Location: Tyler, TX USA
Status:
Offline

TSS Awards Badges

Re: The search for Planet 9

#40

Post by AntennaGuy »


notFritzArgelander wrote: Mon Aug 30, 2021 12:52 am I've started this thread on preferring "gravitational dominance" to "clearing the neighborhood" for classifying different types of planets.
viewtopic.php?f=74&t=20186
Well, I've occasionally found myself in rooms with gravitational-dominant people. There are typically two kinds: (1) those who tend to clear the neighborhoods of anyone in their relatively-wide paths, and (2) those who attract others to orbit around them. In the future, I am tempted to refer to both kinds as "planets."
:dance:
* Meade 323 refractor on a manual equatorial mount.
* Celestron C6 SCT on a Twilight 1 Alt-Az mount
Prof. Barnhardt to Klaatu in The Day the Earth Stood Still: "There are several thousand questions I'd like to ask you.”
Post Reply

Create an account or sign in to join the discussion

You need to be a member in order to post a reply

Create an account

Not a member? register to join our community
Members can start their own topics & subscribe to topics
It’s free and only takes a minute

Register

Sign in

Return to “Solar System”