Vesta is a Planet !

[CraigS]

Is Vesta the 'smallest terrestrial planet?' (http://www.physorg.com/news/2011-12-vesta-smallest-terrestrial-planet.html)



Move over Pluto !

Cheers

[spacezebra]

I'm a pluto supporter and sadly I accepted the IAU findings, however I thought that there were other criterion that had to be satisfied?

Not just geological. Have I missed something here?

Cheers Petra d.

[CraigS]

So Petra … which comes first .. the IAU (the chicken) … or reality (the egg)???

That is the question.

;) :)

Cheers

[Erg]

The definition of planet set in 2006 by the International Astronomical Union (IAU) states that, in the Solar System, a planet is a celestial body which:

1.is in orbit around the Sun,

2.has sufficient mass to assume hydrostatic equilibrium (a nearly round shape), and

3.has "cleared the neighbourhood" around its orbit.

Dont need Dawn to establish any of those 3. IMO they are getting carried away with its beauty. It either fits the def or it doesnt. Doesnt matter how pretty or exciting it is.

Erg

[Poita]

I don't know if I'd call it pretty.
http://upload.wikimedia.org/wikipedia/commons/f/ff/Vesta_Rotation.gif

It may have been a planet under the draft proposal, but not under the current one.
The iron core and volcanic activity make it an interesting study, but it definitely isn't a planet by current definition. It is pretty tiny
http://upload.wikimedia.org/wikipedia/commons/7/72/Iau_dozen.jpg

[renormalised]

If they're going to call Vesta a planet, then they might as well say the Moon really is made of green cheese (Swiss, at that!! :)).

If you take the IAU's ridiculous pronouncement at its literal, strictest meaning, there are no planets in this solar system, except for Mercury and maybe Venus. Every other planet has "debris" in its orbit...think of all the Trojan asteroids floating around about, for a start. Then what about all the other asteroids....the Aten, Amor, Apollo, Centaur and other asteroid groups floating around....all busily orbiting about and near the planets. Cleared orbits???....hardly.

[ballaratdragons]

I'm still waiting for them (IAU) to admit that Earth & Luna is a Double Planet system!

Instead they worry about how Geologically artistic a rock is to make it a planet.
Pretty does not a Planet make!

[ZeroID]

You are a closet 'Luneartharian' ......
From a old Sci Fi I read many moons ago...

The Luneartarians were a mythical people, the original habitants of Earth and the Moon, the only double planet system when space exploration was getting started. And they had powers beyond normal humans ...
Can't remember what the book was called or the author.

Might have been spelled Lunartharian, not sure. I'm off to google ...:question:

[higginsdj]

Gee wiz - NASA's ignoring the rules and making up it's own names and titles - now there's something new.........

What better way to keep oneself at the forefront of pulicity than to make big, bold statements - who cares if they are true!

Cheers

[renormalised]

FY2012 is coming up, and NASA looks like it's possibly loosing a few billion in funds. So, you know what this is being done for:)

[Kal]

I take issue with them using the term 'terrestrial'.

Doesn't that imply that it is from earth?

[renormalised]

Strictly speaking, yes. However when used in this context it refers to rocky planets....as you'd already know.

[TrevorW]

What gives the IAU the right to detemine that Pluto isn't a planet yet some small chunk of rock is

as far as I'm concerned Pluto is a planet as well as Mickey, Donald and Dopey

[N1CK06]

They are suggesting that Vesta should be categorised as a "dwarf planet", which puts it in the same class as what Pluto has been demoted to. Among these is the dwarf planet Ceres which the Dawn probe will be passing sometime in 2015 which is also located in the asteroid belt.

I suppose there could be many more dwarf planets in our solar system that fit in with IAU's classifications which haven't been accepted as dwarf planets yet.

Cheers,
Nick

[snas]

My question is, what is the origin of the lines that seem to run around Vesta's "equator" on Peter's .gif http://upload.wikimedia.org/wikipedia/commons/f/ff/Vesta_Rotation.gif

Stuart:shrug:

[N1CK06]

Good question! I was curious myself and found this interesting article which mentions them: http://planetary.org/blog/article/00003233/

It seems they relate to the large impact basins at Vesta's south pole which indicates they may have formed as a result of a large collision with an asteroid. I'm not too sure exactly how they came to be though..

My guess is that the impact has caused the surface to deform as a response to the force of the collision. This also agrees with the article in the original post which mentions tectonic features.

[renormalised]

You've pretty much hit the nail on the head there, Nick. They're ripples caused by the impact of large bodies on the surface of the asteroid. Actually, they're akin to ripples in water when you drop a rock into it, only in this case it's deformation occurring in the rocks, that were formed by powerful shockwaves. In very large earthquakes here on Earth, you can occasionally see these waves pass through the surface layers of the crust...as a rippling effect. You'll also see them formed in major asteroid impacts on the terrestrial planets as well.

[Ric]

Hi Carl

Would they be the same as a Love or Rayleigh wave here on Earth?

[renormalised]

Similar, but far more energy and faster. Normally Love/Rayleigh waves don't physically deform the rocks (unless they're generated by a big quake) . The shockwaves from a major impact visibly deform the surrounding rocks. In terms of water waves, they'd be more akin to tsunamis than wind driven surface waves.

[N1CK06]

So these ripples would have to suggest that Vesta has a crust. And if the size and force of the collision that caused the ripples can be determined from analysing the impact basin then the crustal thickness, density and maybe even the rock type could also be determined. They could tell a lot about this "planet". Although I'm sure the Dawn probe has equipment that can determine this in a much easier way.

[renormalised]

Yes....however, a body doesn't have to have a crust for these types of waves to be generated by an impact. Any large impact (or small one for that matter) with generate longitudinal waves in the body of the impacted object. The results of the waves travelling through the body depend on the size of the impact.

[N1CK06]

So if Vesta was a uniform body (by this I mean a solid rock throughout with no differentiation) would you still see the lines/ripples/troughs/whatever-you-call-it near the equator?

Geologically speaking I'm trying to see a similarity with the process of mountain building here on Earth. i.e. Two pieces of crust colliding together and crumpling causing intense deformation and hence mountains. Only in this case replacing once piece of crust with a large asteroid and the other with Vesta's surface. (of course ignoring time-scales here because there would be a HUGE difference between the two events!).

[renormalised]

Yes.....the composition of the rock is immaterial. It's how big the impactor is as to whether it will deform the rock in that fashion. All impacts will produce longitudinal waves in the rocks, it's just that most of them won't produce visible ones because they're not large enough to deform the rocks in that way.

No similarity at all to mountain building. One is due to tectonic process, the other is due to one off cataclysmic processes. Different scales of deformation, energy involved, different types of deformation, speed of the deformation etc etc etc.