Solar Scale

[rossk]

Haha, like the dwarf planet render

 

As I understand it (and I may be wrong) pluto is classified as a dwarf planet because it hasn't cleared its path of other objects (in this case being neptune)?

And if that is the case, wouldn't neptune be demoted also?

[Stuart Rogers]

As I understand it (and I may be wrong) pluto is classified as a dwarf planet because it hasn't cleared its path of other objects (in this case being neptune)?

And if that is the case, wouldn't neptune be demoted also?

That occurred to me too, and I now learn that some IAU members are up in arms over the new definition because of anomalies such as this.

 

Given that they're trying to make arbitrary classifications over a smooth spectrum of objects, I think they're on a hiding to nothing - whatever definition they use there'll be something that doesn't quite fit.

[Julian]

As I understand it (and I may be wrong) pluto is classified as a dwarf planet because it hasn't cleared its path of other objects (in this case being neptune)?

When they say Pluto hasn't cleared its "neighborhood" of other objects, they're talking about Charon and the entire rest of the Kuiper Belt.

[DanCBradbury]

Then wouldn't halley's comet then null out all of the planets, as it does cross all of them

[Stuart Rogers]

When they say Pluto hasn't cleared its "neighborhood" of other objects, they're talking about Charon and the entire rest of the Kuiper Belt.

By that token, Earth isn't a planet because it hasn't cleared the Moon from its orbit. And Jupiter isn't a planet because it shares its orbit with dozens of Trojan asteroids which it hasn't cleared, and probably never will given that they occupy the L4 and L5 Lagrangian points. It'll all end in tears!

[Julian]

By that token, Earth isn't a planet because it hasn't cleared the Moon from its orbit.

Charon qualifies as a co-dwarf planet with Pluto, because Charon and Pluto orbit around a common barycenter which lies above Pluto's surface. "Clearing a planet's neighborhood" in this context refers to clearing all the other objects in the debris ring within the early solar system that condensed to form that planet. The Trojan asteroids don't apply because they were probably captured later.

 

When the Earth's Moon was formed from a collision between the Earth and a Mars-sized object, that would probably have been Earth's last major neighborhood-clearing event.

[OdinsEye2k]

Yeah, clearing the neighborhood is going to be a kind of confusing definition for non-experts (and probably some dueling between them as well).

 

The Trojans of Jupiter are a good point, although they orbit in Jupiter's gravitational Lagrange points, so you could argue that they are already "captured" by Jupiter (actually, looks like the Wiki article agrees with me). If any asteroid leaves those two zones, they are likely leaving that orbit as they encounter Jupiter's gravity.

 

Neptune and Pluto don't really share an orbit, they just cross over each other once in a while, but Pluto is really out of the plane that the other eight planets roughly share.

 

This is pretty wild below. The gas giants are actually weaker in clearing their brethren away than, say Earth or Venus. It probably has to do with how much bigger in space the outer orbits are.

 

http://en.wikipedia.org/wiki/List_of_solar...ry_discriminant

[MattWBradbury]

I am having a rather tough time figuring out what clearing an neighborhood.

 

I was hopping for a definition (of a planet) that would state that planets must be a sphereroid, must be at least 1,000 km in radius, and must have a primary orbital vector around the star. No such luck there

 

I wonder how they are going to explain clearing the neighborhood to kindergarden students.

[OdinsEye2k]

Dunno about kindergarten, but a couple of grades later it's easier.

 

Defining a planet seems like defining the class bully. If it's big and aggressive, it's a planet.

[DanCBradbury]

Dunno about kindergarten, but a couple of grades later it's easier.

Can someone please think of the children

 

[Muff]

NICE! Those are impressive renders! Not to mention the Planets. Nice texturing! But I Love those Renders.

[jpappas]

Hey,

 

Thought this thread was a good place for this. Found a website with incredible pictures of the sun, (and I think it's updated every few minutes from a satellite):

 

http://soho.esac.esa.int/data/realtime/eit_304/#

 

-Jim