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The search for Planet 9 ...join in

macdoc

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macdoc
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Planet earth on slow boil
For those down under

256f9662d3e61f6cb975d4a151c75f88


British cosmologist Brian Cox will tonight press gang Australian TV viewers into the search for the solar system’s darkest planet, in a broadcast filmed at a craggy NSW peak.

The youthful looking particle physicist, also known as host of the BBC’s Stargazing Live program and former keyboardist with pop band D: Ream, will recruit citizen scientists during an ABC broadcast of the program. It was recorded last week at the Australian National University’s SkyMapper telescope at Siding Spring near Coonabarabran.

Professor Cox used the program to launch ANU’s crowdsourced project to find “Planet 9”, a hypothetical planet orbiting far beyond Neptune.
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http://www.theaustralian.com.au/hig...n/news-story/37811e566e0bd685ae427dbd36bf9ead

Lots of cool hands on science with an interactive aspect that drew a million fresh crowd sourced analysis

Join in the hunt

https://www.zooniverse.org/projects/skymap/planet-9
 
3point14 said:
We had a planet nine once.

Poor Pluto.
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I would've prefered if instead of creating a confusing terminology where dwarf planets aren't planets, they'd just split "planet" in two: major and minor. That way you'd still say there are eight major planets in the system, and possibly dozens or thousands of minor ones.
 
3point14 said:
We had a planet nine once.

Poor Pluto.
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Actually it was the tenth planet - everyone forgets about Ceres...:)

Argumemnon said:
I would've prefered if instead of creating a confusing terminology where dwarf planets aren't planets, they'd just split "planet" in two: major and minor. That way you'd still say there are eight major planets in the system, and possibly dozens or thousands of minor ones.
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Interestingly, some planetary scientists would agree with you on this...
 
Argumemnon said:
I would've prefered if instead of creating a confusing terminology where dwarf planets aren't planets, they'd just split "planet" in two: major and minor. That way you'd still say there are eight major planets in the system, and possibly dozens or thousands of minor ones.
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I actually prefer the classification of planet as anything big enough to clear it's orbit of any other debris.

Anything that hasn't isn't really a planet, dwarf or otherwise.

Otherwise there seems to be no way to discern between 'dwarf planet', 'large asteroid' or 'large KBO'
 
Argumemnon said:
I would've prefered if instead of creating a confusing terminology where dwarf planets aren't planets, they'd just split "planet" in two: major and minor. That way you'd still say there are eight major planets in the system, and possibly dozens or thousands of minor ones.
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Isn't that how it works already with dwarf planets?

Wiki says there's five official dwarf planets: Ceres, Pluto, Haumeau, Makemake, and Eris;

another six that'll be approved eventually: Quaoar, 2002 MS4, Sedna, Orcus, Salacia, and 2007 OR10;

and hundreds to thousands estimated to exist.
 
3point14 said:
I actually prefer the classification of planet as anything big enough to clear it's orbit of any other debris.

Anything that hasn't isn't really a planet, dwarf or otherwise.

Otherwise there seems to be no way to discern between 'dwarf planet', 'large asteroid' or 'large KBO'
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Dwarf planets have hydrostatic equilibrium.
 
3point14 said:
I actually prefer the classification of planet as anything big enough to clear it's orbit of any other debris.

Anything that hasn't isn't really a planet, dwarf or otherwise.

Otherwise there seems to be no way to discern between 'dwarf planet', 'large asteroid' or 'large KBO'
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The problem with this definition, if I understand correctly, is verifying the absence of debris in its orbit.

It may not be hard to do close in, but Pluto's orbit takes it on quite a lengthy journey. Lots of space for a hunk of rock to be sitting out there.

But maybe I'm wrong...
 
I'm a fan of the big enough to be a ball definition (mentioned above.) Don't care if it is in orbit about something besides the sun, nor if there is other smaller non-ball junk in its orbit.
 
What else is in Pluto's orbit that it hasn't been cleared? What about stuff in Lagrange points - do those count as "stuff in the neighborhood" that hasn't been cleared by the planet?
 
Argumemnon said:
Dwarf planets have hydrostatic equilibrium.
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Is that binary? I thought that got fuzzy at the edges?

That said, as others have pointed out, I'm not sure that the definition of planetary is quite as black and white as I thought it was.
 
Beerina said:
I'm a fan of the big enough to be a ball definition (mentioned above.) Don't care if it is in orbit about something besides the sun, nor if there is other smaller non-ball junk in its orbit.
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The issue was that there might be thousands of bodies that fit that definition in the solar system, making planet lists a bit cumbersome.
 
3point14 said:
Is that binary? I thought that got fuzzy at the edges?
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What do you mean? That's part of the definition.

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

A dwarf planet is a planetary-mass object that is neither a planet nor a natural satellite. That is, it is in direct orbit of the Sun, and is massive enough for its gravity to crush it into a hydrostatic equilibrium shape (usually a spheroid), but has not cleared the neighborhood of other material around its orbit.[1]
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Emily's Cat said:
What else is in Pluto's orbit that it hasn't been cleared? What about stuff in Lagrange points - do those count as "stuff in the neighborhood" that hasn't been cleared by the planet?
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https://en.wikipedia.org/wiki/Clearing_the_neighbourhood

In the end stages of planet formation, a planet (as so defined) will have "cleared the neighbourhood" of its own orbital zone, meaning it has become gravitationally dominant, and there are no other bodies of comparable size other than its satellites or those otherwise under its gravitational influence. A large body that meets the other criteria for a planet but has not cleared its neighbourhood is classified as a dwarf planet. This includes Pluto, which is constrained in its orbit by the gravity of Neptune and shares its orbital neighbourhood with Kuiper belt objects.
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