# Hello Pluto!



## John P (Sep 1, 1999)

Nine years after launch, the New Horizons probe zipped past Pluto at 7:49 AM eastern today.

http://www.nasa.gov/mission_pages/newhorizons/main/index.html

I love that it's sorta orange, just like Mickey's dog.


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## spock62 (Aug 13, 2003)

Pluto, the _planet_ nobody respects:


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## Richard Baker (Aug 8, 2006)

(image edited for language)


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## Frank2056 (Mar 23, 2007)

I think it's great to finally get an image of the nine planets of my childhood, but this image from Pando at unmannedspaceflight is a good illustration as to why Pluto was demoted to a dwarf planet. Triton is the largest moon of Neptune and often considered a Pluto analog. The Moon, everyone knows. Pluto is not only 70% the size of our Moon, it's much less massive:


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## BWolfe (Sep 24, 2013)

So true!


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## Frank2056 (Mar 23, 2007)




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## SUNGOD (Jan 20, 2006)

Great pics but it's a shame these planets turn out to be different colours than previously thought.


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## Richard Baker (Aug 8, 2006)

SUNGOD said:


> Great pics but it's a shame these planets turn out to be different colours than previously thought.


That is actually one of my favorite things- we can see them for the first time as if we are in the neighborhood. All my life everything was conjecture, educated guesses, artistic renderings... - now we know for sure if we were to go there and look out the window this is exactly what it will look like- right down to which crater is next to what mountain. 

I think that is very cool...


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## Frank2056 (Mar 23, 2007)

SUNGOD said:


> Great pics but it's a shame these planets turn out to be different colours than previously thought.


It's been known for years that Pluto is red/reddish and has large brightness variations on its surface.


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## Zombie_61 (Apr 21, 2004)

SUNGOD said:


> Great pics but it's a shame these planets turn out to be different colours than previously thought.


Up next - Why dinosaurs don't actually look like large reptiles like we think they do.


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## SUNGOD (Jan 20, 2006)

I suppose that's some good points about the colours but I think it was Neptune and Uranus now look more grey (or gray to you folk over the pond) than the blue and greenish colours we used to think they were. I find that a bit of a let down as the old colours made them look quite striking.

As for dinosaurs...............I really don't like this feathered lark. I prefer to think of them as more monster/lizard like than giant birds.


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## SUNGOD (Jan 20, 2006)

Looks like some incredible ice cliffs on Pluto from the clearer photos today. 2 miles high


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## spock62 (Aug 13, 2003)

SUNGOD said:


> As for dinosaurs...............I really don't like this feathered lark. I prefer to think of them as more monster/lizard like than giant birds.


I agree, I like the "old school" dinosaurs:


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## charonjr (Mar 27, 2000)

The only reason Pluto was re-classified is so that every Kuiper Belt object doesn't make it into the "planet" category. The fact that it is neither gas giant nor totally rocky really has nothing to do with it. Mercury is a little larger than the Moon, but 2/3s the size of Mars. It is considered a planet merely because there are not many rocky worlds to add to the number.

However, with the evident geological activity, the very youth of the surfaces of both Pluto and Charon (pronounced Char (as in Charlene) -on may change the classification yet again. 

BTW, my Dad, James W. Christy, discovered Charon in 1978. It is named after his second wife, my step-mother. So if anyone says "sharon", punch them in the shoulder and correct them.


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## Frank2056 (Mar 23, 2007)

charonjr said:


> The only reason Pluto was re-classified is so that every Kuiper Belt object doesn't make it into the "planet" category. The fact that it is neither gas giant nor totally rocky really has nothing to do with it. Mercury is a little larger than the Moon, but 2/3s the size of Mars. It is considered a planet merely because there are not many rocky worlds to add to the number.


If you line up all the terrestrial planets and go just by size, Pluto is puny in comparison even to Mercury. If you compare the terrestrials by mass, it's not even a fair fight - Pluto is a feather compared (once again) to Mercury, or even the Moon (the Moon is 5.6x more massive). Pluto just doesn't fit in with the planets. It's a good example of a different category of objects and it's not even the most massive of the Kuiper belt objects (Eris is).




charonjr said:


> BTW, my Dad, James W. Christy, discovered Charon in 1978. It is named after his second wife, my step-mother. So if anyone says "sharon", punch them in the shoulder and correct them.


I met you at The Hobby Place (now long gone) in LA about 20 years ago+/-


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## Zombie_61 (Apr 21, 2004)

That's no moon...


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## John P (Sep 1, 1999)

charonjr said:


> BTW, my Dad, James W. Christy, discovered Charon in 1978. It is named after his second wife, my step-mother. So if anyone says "sharon", punch them in the shoulder and correct them.


Wow! That's something to be proud of!


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## hal9001 (May 28, 2008)

SUNGOD said:


> I suppose that's some good points about the colours but I think it was Neptune and Uranus now look more grey *(or gray to **you folk over the pond)*


Well SUNGOD, it's everyone's God given right to spell things wrong sometimes....we forgive y'all....

Carl-


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## StarshipClass (Aug 13, 2003)




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## SUNGOD (Jan 20, 2006)

hal9001 said:


> Well SUNGOD, it's everyone's God given right to spell things wrong sometimes....we forgive y'all....
> 
> Carl-




Tanks four tha fourgivvnnesss butt eye taught hour sppellyn was oh-key.


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## charonjr (Mar 27, 2000)

If we use object classification based on mass, then, in fashion, none of the objects can be strictly called a planet. We have small rocky orbiters, large rocky ones like Earth, then small and large gas orbiters. The fact that distant orbiters are numerous and made of light materials shouldn't be the sole reason for classifying them as a planet. The first eight objects and the Kuiper Belt objects, of which Pluto is considered the inner most one, still orbit the Sun. Classification is only a tool of convenience.

The first nine objects found orbiting the Sun were discovered via eye and telescope due to there brightness. What happens if a brown dwarf star is discovered? Are we to consider it a "star", a planet because it orbits the Sun? Or a new class of orbiting objects?

My point is such classification already reduces the number of "planets" based on an arbitrary definition. Four rocky worlds, four gas worlds, one ice world with a very large moon and four smaller moons, and an unknown number of Kuiper Belt "objects". It's a very thin line we are drawing that isn't based on rigorous science, but on an emotional feeling that Pluto can't be a planet because there would be too many of them, including Eris.

Pluto orbits and behaves like a planet, right down to geological processes and having moons. Something that not even Mercury nor Venus can claim in terms of having moons.

But that's okay. I doubt the Astronomical Society will reverse themselves. So, Ice Dwarf Kuiper Belt object it is.


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## John P (Sep 1, 1999)

Some say that if Pluto is a planet, then so should Ceres, Eris, Makemake, et al be planets. Fine with me! The more the merrier, sez I. I'd rather see the family grow than shrink!


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## MartyS (Mar 11, 2014)

charonjr said:


> Pluto orbits and behaves like a planet,


That's where you're argument breaks down, it was the orbit that was the main reason Pluto got demoted to dwarf planet. The 8 major planets have orbits that are in the same plane, and don't cross each other. Pluto has a very inclined orbit and it crosses inside the orbit of Neptune. Just look at a 3D representation of the orbits and Pluto stands out pretty dramatically.

There's a cool webpage based 3D model here:

http://www.brightonastronomy.com/solarsystem.html

Some have lobbied for Pluto to be grandfathered back in, but that's not how science works, things either fit a definition or they don't. It really should have been reclassified decades ago, but until other dwarf planets were discovered there wasn't much impetus to do so.


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## GSaum (May 26, 2005)

MartyS said:


> Some have lobbied for Pluto to be grandfathered back in, but that's not how science works, things either fit a definition or they don't. It really should have been reclassified decades ago, but until other dwarf planets were discovered there wasn't much impetus to do so.


Yep, and some need to remember that they were arguing whether Pluto was a planet or not for decades, not just the last few years. Long before they discovered other Kuiper Belt Objects astronomers debated on whether Pluto really should be considered a planet. Frankly, I think there's too much emotion involved in this. If you want to consider Pluto a planet, go for it. However, it officially is not a planet, nor should it be because it does not fit the definition. Also, keep in mind that the asteroid Ceres was considered a planet for hundreds of years until the mid-to-late 1800s when other similar objects were discovered in the Asteroid Belt. If people could let go of that notion, they can let go of Pluto. Just get over it already.


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## Fozzie (May 25, 2009)

GSaum said:


> However, it officially is not a planet, nor should it be because it does not fit the definition.


So how do we explain all the sci fi shows and movies set in the future that mention 9 planets in the Sol system?


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## MGagen (Dec 18, 2001)

Obviously, it's the Doppelganger Earth that orbits on the other side of the sun from us!

Gerry Anderson has all the answers...


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## hal9001 (May 28, 2008)

MGagen said:


> Obviously, it's the Doppelganger Earth that orbits on the other side of the sun from us!
> 
> Gerry Anderson has all the answers...


He's a piece of wood, don't believe him! _Wood has always been know to lie_...

Carl-


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## Frank2056 (Mar 23, 2007)

Pluto was classified as a planet only because it was assumed to be the object causing a perturbation in the positions of Uranus and Neptune. Estimates of Pluto's mass varied widely, from much more massive than the Earth to relatively tiny. It was eventually discovered that the perturbations in the orbits of the ice giants was just a error. And Pluto's mass was miniscule.

That said, Pluto is a very strange world. Some of the recent images show really puzzling structures never seen on any other world. It may be due to the way Pluto and Charon formed or because this is the first Kuiper belt object we've looked at closely or because organic chemistry at 40K to 50K is complex. 
It's too bad we don't have the money/technology to put an orbiter around Pluto.


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## charonjr (Mar 27, 2000)

I should point out that while Pluto's orbit is different than the inner 8 worlds, both Neptune and Uranus are oddities in their own right. Uranus's pole points in the direction of the Sun, it's moons orbits aligned with its equator, not the Ecliptic Plane. As of yet, there is no explanation for this orientation. Neptune, planet 8, is inclined axially like Earth, but has an inclined, elliptical orbit. It's outermost moon, Triton, is in a retrograde orbit, unlike the rest of Neptune's moons. It is thought that Triton is a captured Kuiper Belt object.

While we have not yet discovered the "Planet X" that is affecting both Uranus' and Neptune's orbits, it is such a gravitational anomaly that is responsible for Neptune's discovery and later, Pluto's. 

Scholz's star, a dim red dwarf with a brown dwarf companion, passed within 0.8 light years (5 trillion miles) of us about 70,000 years ago. This is within the Oort Cloud. It would have caused comet showers as it passed through. It is about 20 light years away now. 

I am curious if such an object might have been responsible for Pluto's and Neptune's inclined orbits, Triton's capture, and the axial inclination of Uranus and its moons.


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## MartyS (Mar 11, 2014)

charonjr said:


> Scholz's star, a dim red dwarf with a brown dwarf companion, passed within 0.8
> 
> ...
> 
> I am curious if such an object might have been responsible for Pluto's and Neptune's inclined orbits, Triton's capture, and the axial inclination of Uranus and its moons.


Nope, too far away for such a small mass to affect the large planets. Any comets in the immediate area would have their orbits changed, but that's about it.

Think about it this way, Jupiter barely has an influence on the inner solar system at a few hundred million miles, something only a few times larger (red dwarf star) at trillions of miles would have practically no influence.

The reason more planet Xs haven't been found is because objects out there could have orbits that last thousands of years, and there isn't much sunlight out there to light them up, and they generally have low surface reflectivity. That adds up to them being nearly undetectable until they come in closer.


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## Frank2056 (Mar 23, 2007)

charonjr said:


> While we have not yet discovered the "Planet X" that is affecting both Uranus' and Neptune's orbits, it is such a gravitational anomaly that is responsible for Neptune's discovery and later, Pluto's.
> ...
> 
> I am curious if such an object might have been responsible for Pluto's and Neptune's inclined orbits, Triton's capture, and the axial inclination of Uranus and its moons.


The early solar system was a very chaotic place, and the gas giants (including Uranus and Neptune) didn't form anywhere near their current positions (but still past the solar system's ice line).

The Nice (as in France) Model (and variants) for the Solar System's formation do a fairly good job of explaining the process. In some versions, a fifth ice giant got ejected from the system.

You also have to consider the Sun's natal open cluster. It's possible that the Sun and its nearby sister suns traded objects near their outer reaches. There are large KBOs (like Sedna) whose orbits are very difficult to explain. It's possible that Sedna was originally orbiting another star.


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## scotpens (Sep 6, 2003)

Frank2056 said:


> I think it's great to finally get an image of the nine planets of my childhood, but this image from Pando at unmannedspaceflight is a good illustration as to why Pluto was demoted to a dwarf planet.


Pluto wasn't "demoted"; it was simply reclassified. It's not like dwarf planets have fewer perks and privileges than planets. Does anyone really think Pluto gives a damn what we call it?


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## Owen E Oulton (Jan 6, 2012)

If Peter Dinklage and Warwick Davis are still Human beings, the Pluto is still a Planet. It's all semantics.


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## mcdougall (Oct 28, 2007)

That's proof enough for me....Burn the Witch !

Mcdee


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