9th planet (nearly) found?

[nytecam]

Brown's paper interesting but not unique and makes a statement of intent for which he's well qualified.  Good to see how it pans out.   Recorded Eris @ m18.75 last year but Panet 9 is going to be much fainter but well within range of pro survey scopes.

Nytecam

[Mr Spock]

I'll believe it when I see it

[Ouroboros]

It supposedly 12 times as far away as pluto, so I make that 144 times less sunlight, then 144 times less light getting back to earth =~ 20,000 times fainter, other things being equal. Obviously if bigger than Pluto it could be reflecting rather more.

Yes, that's why my earlier back of the envelope calc is wrong. I only took into account the 144 times less sunlight, not the return journey. Hey ho!

[Jase_v2]

Just waiting for all the fruitloops to come out of the woodwork and tell us that Planet x/Nubaru (or whatever they call it) has been found!

The Reptoid inhabitants have obviously left their cloaking device off .       

you beat me to it

[LukeSkywatcher]

It supposedly 12 times as far away as pluto, so I make that 144 times less sunlight, then 144 times less light getting back to earth =~ 20,000 times fainter, other things being equal. Obviously if bigger than Pluto it could be reflecting rather more.

In other words..........completely invisible to most if not all of us.

That far away..........can it even be considered to be within our solar system.

I am, and always be of the opinion that Pluto is the 9th planet in our solar system..................i dont give a single iota what the IAU say.

Recent pics have proven its planetary status........................

[Dave Lloyd]

An astrologer chappie in the paper the other day was saying that it will make for some exciting changes. The fact they didn't know it existed obviously accounts for the fact that my horoscopes are always wrong.

[DaveS]

 

On ‎22‎/‎01‎/‎2016 at 21:42, LukeSkywatcher said:

In other words..........completely invisible to most if not all of us.

That far away..........can it even be considered to be within our solar system.

I am, and always be of the opinion that Pluto is the 9th planet in our solar system..................i dont give a single iota what the IAU say.

Recent pics have proven its planetary status........................

I think the limit of the Solar System is defined (Or not, it's so diffuse) by the Oort cloud, at (Theoretically) nearly 1 LY from the Sun, so Planet 9 is definitely part of the solar System. I suspect there's a heck of a lot out there still to find, hopefully with some big (But not lethal) surprises.

[digital_davem]

On 22/01/2016 at 21:42, LukeSkywatcher said:

In other words..........completely invisible to most if not all of us.

That far away..........can it even be considered to be within our solar system.

I am, and always be of the opinion that Pluto is the 9th planet in our solar system..................i dont give a single iota what the IAU say.

Recent pics have proven its planetary status........................

As fascinating as Pluto undoubtedly is, I suggest reading what Mike Brown has to say on the subject, rather than just the IAU. Essentially, Pluto is (the largest known) member of a fascinating family of objects that share similar characteristics and which are distinct from both the gas/ice giant worlds and the inner terrestrial planets in their properties (and likely, formation). These Kuiper belt objects are worthy of study in their own right and Pluto is right up there as a stereotypical member (as is Charon).  There are already a bunch of discovered similar worlds starting with Eris that are equally entitled to be called planets if Pluto is to be regarded as a planet. Potentially there are hundreds waiting to be found. It is historical accident that Pluto was the first discovered and its only claim to be a planet. Pluto and the other KBOs have a story to tell that will reveal more about the structure and origin of our solar system. Let's not obsfuscate that important journey with childish emotional stamp collecting squabbles over Pluto's status and get on with finding out what KBOs have to tell us about how we got here...

[Stub Mandrel]

20 hours ago, digital_davem said:

As fascinating as Pluto undoubtedly is, I suggest reading what Mike Brown has to say on the subject, rather than just the IAU. Essentially, Pluto is (the largest known) member of a fascinating family of objects that share similar characteristics and which are distinct from both the gas/ice giant worlds and the inner terrestrial planets in their properties (and likely, formation). These Kuiper belt objects are worthy of study in their own right and Pluto is right up there as a stereotypical member (as is Charon).  There are already a bunch of discovered similar worlds starting with Eris that are equally entitled to be called planets if Pluto is to be regarded as a planet. Potentially there are hundreds waiting to be found. It is historical accident that Pluto was the first discovered and its only claim to be a planet. Pluto and the other KBOs have a story to tell that will reveal more about the structure and origin of our solar system. Let's not obsfuscate that important journey with childish emotional stamp collecting squabbles over Pluto's status and get on with finding out what KBOs have to tell us about how we got here...

The more I consider the issue, the less I agree.

Classifying these things into 'planets', 'minor planets', 'kuiper belt objects', 'dwarf planets' etc. is essentially even more arbitary that the classification of species in biology. Any biologist worthy of the name will admit that 'species' are fluid concepts whose purpose is solely to allow us to describe and distinguish different groups of animals and the boundaries between them do not necessarily have any fixed or objective meaning independent of human opinion.

Looking at 'large lumps of orbiting matter' it's pretty clear that in many cases their are few absolute classes of object - rocky ones, icy ones and gassy ones, perhaps?  The biggest grade into stars at the top end and the smallest just peter out into interstellar dust grains. The biggest moons and smallest 'planets' are indistinguishable except by whether they orbit the moon or a larger body. If 'planet IX' really is a semi-neptune it will still not qualify as a planet under current rules as the presence of the bodies that  are hinting at its presence have not been cleared from its orbit - hence it fails one of the new 'planet tests'.

If the Earth didn't have humans living on it, the Earth-Moon system (and Pluto-Charon) could be considered a double planet - and it will meet the present criterion in the distant future. When the moon drifts a fractional amount further from the earth one day and becomes a planet in its own right (according to the IAU) will anything about it have materially changed?

So, I think that any definition of 'planet' is fundamentally arbitrary it might be really important to follow the rules if you are doing your Astronomy BSc final exams, but in practice if anyone calls Pluto a planet they have as much right to do so as to believe that dogs and wolves are different species or that dandelions are a single species of plant (estimates range between 60 and 2000 species).

Perhaps one truth is that there are dozens (and maybe hundreds?) of bodies that could be worthy of the title 'planet', and maybe instead of reserving that title for all the ones we can see with the naked eye (plus Uranus and except the Moon) we should use the term more loosely and instead concentrate on making meaningful subdivisions of the concept. This would address the very real issue that as 'planet' cannot be used there is no single word for 'massive body in orbit around a star or another body'.

As a final thought, looking at the incredible diversity of pla^H^H^H 'massive bodies in orbit around the Sun and each other' in the Solar System it should be fairly obvious that when/if we start to find smaller objects around other stars then the diversity is going to be even greater and the chance that the carefully argued criteria for Sun-bound planets will prove meaningful in the context of a galaxy, let alone a universe, full of a massive variety of 'planetary systems' must be vanishingly small.

 

[digital_davem]

On 28/01/2016 at 21:38, Stub Mandrel said:

The more I consider the issue, the less I agree.

Classifying these things into 'planets', 'minor planets', 'kuiper belt objects', 'dwarf planets' etc. is essentially even more arbitary that the classification of species in biology. Any biologist worthy of the name will admit that 'species' are fluid concepts whose purpose is solely to allow us to describe and distinguish different groups of animals and the boundaries between them do not necessarily have any fixed or objective meaning independent of human opinion.

Looking at 'large lumps of orbiting matter' it's pretty clear that in many cases their are few absolute classes of object - rocky ones, icy ones and gassy ones, perhaps?  The biggest grade into stars at the top end and the smallest just peter out into interstellar dust grains. The biggest moons and smallest 'planets' are indistinguishable except by whether they orbit the moon or a larger body. If 'planet IX' really is a semi-neptune it will still not qualify as a planet under current rules as the presence of the bodies that  are hinting at its presence have not been cleared from its orbit - hence it fails one of the new 'planet tests'.

If the Earth didn't have humans living on it, the Earth-Moon system (and Pluto-Charon) could be considered a double planet - and it will meet the present criterion in the distant future. When the moon drifts a fractional amount further from the earth one day and becomes a planet in its own right (according to the IAU) will anything about it have materially changed?

So, I think that any definition of 'planet' is fundamentally arbitrary it might be really important to follow the rules if you are doing your Astronomy BSc final exams, but in practice if anyone calls Pluto a planet they have as much right to do so as to believe that dogs and wolves are different species or that dandelions are a single species of plant (estimates range between 60 and 2000 species).

Perhaps one truth is that there are dozens (and maybe hundreds?) of bodies that could be worthy of the title 'planet', and maybe instead of reserving that title for all the ones we can see with the naked eye (plus Uranus and except the Moon) we should use the term more loosely and instead concentrate on making meaningful subdivisions of the concept. This would address the very real issue that as 'planet' cannot be used there is no single word for 'massive body in orbit around a star or another body'.

As a final thought, looking at the incredible diversity of pla^H^H^H 'massive bodies in orbit around the Sun and each other' in the Solar System it should be fairly obvious that when/if we start to find smaller objects around other stars then the diversity is going to be even greater and the chance that the carefully argued criteria for Sun-bound planets will prove meaningful in the context of a galaxy, let alone a universe, full of a massive variety of 'planetary systems' must be vanishingly small.

 

There are some useful group distinctions to make, I think.  For example, Mercury, Venus, Earth, Mars are all small rocky bodies, Jupiter, Saturn are basically clouds of hydrogen and helium, uranus and neptune largely gas but with a higher proportion of ices.  Of the moons, only Luna and Io are rocky, the others are very much less dense and icy.  KBOs also tend to be icy and small. 

These bulk compositional differences and smilarities likely tells us much about the origin of these worlds -eg icy moons and KBOs are unlikely to have formed close in to sun as the volatiles would have burned off.  Pluto appears to be a KBO type world with much in common with other KBOs. If this turns out to be the case and the mechanism of formation of KBOs is eventually worked out and is confirmed to be different from gas giants and terrestrial worlds, we would only confuse matters to insist on calling it a planet for nothing other than historical reasons.  The IAU has tried to draw up a set of rules that may or may not make sense but there is more than arbritrariness behind it.  The furore over Pluto's demotion is largely nothing to do with science anyway. A few vested interests (New Horizons, anyone...) and lots of people who learned the names of nine planets at school and are clinging to them out of nostalgia.

KBOs (including Pluto) are fascinating and as a class of bodies deserve to regarded as every bit as important as the planets and these primordial bodies have lots to tell us.

 

 

[Stub Mandrel]

10 hours ago, digital_davem said:

There are some useful group distinctions to make, I think.

 

Indeed, but aside from having the mass to assume a broadly spherical shape, none of these origin, composition or size distinctions that may have some objective 'meaning' relates meaningfully to the IAU definition of planet.

[digital_davem]

9 minutes ago, Stub Mandrel said:

Indeed, but aside from having the mass to assume a broadly spherical shape, none of these origin, composition or size distinctions that may have some objective 'meaning' relates meaningfully to the IAU definition of planet.

The important thing is that we work on understanding the formation of the solar system. Pluto and the other KBOs have an important role to play way beyond what they are called. The weirdest factoid of all for me is that the current favoured planetary formation model (the acretion model) appears to be impossible as, while it is certainly possible to explain how dust particles combine to form pebbles, there is no known mechanism by which metre sized rocks colliding at 40,000 mph can acrete into a planetesimal...

[Mav359]

If your a planetary imager with the full set and rightly proud of the feat surely you dont want someone coming along and anoouncing that "we found it" at which point you'll realise you set is never going to be complete..... My OCD couldn't handle it

[Stub Mandrel]

4 hours ago, Mav359 said:

If your a planetary imager with the full set and rightly proud of the feat surely you dont want someone coming along and anoouncing that "we found it" at which point you'll realise you set is never going to be complete..... My OCD couldn't handle it

So show me your pic of 'Earth'!

[Mav359]

1 hour ago, Stub Mandrel said:

So show me your pic of 'Earth'!

good point