Starship Asterisk*

by **JohnD** » Tue Oct 16, 2007 8:58 pm

We call that schoolboy humour.

Very funny,CC.

John

by **craterchains** » Tue Oct 16, 2007 5:17 pm

uhmmm , JohnD?

OOOOO000O0O0OO000

you may want to edit that post, ,

"To penetrate as you suggest would require a dense impactor and very low density, or etc"

Reads kinda funny this way, , grins

by **JohnD** » Tue Oct 16, 2007 1:44 pm

nateleavitt wrote:How about another far-fetched theory ...

On object struck it with such force that it penetrated the surface and lodged itself somewhere near the core of the planet.

Large impactors usually strike with so much energy that they splash, rather than shatter, let alone stay intact. Small meteorites can land intact, as they slow enough in an atmosphere, which Japetus doesn't have. To penetrate as you suggest would require a dense impactor and very low density, or liquid object impacted.

John

by **craterchains** » Sun Oct 14, 2007 3:10 am

BMAONE23 wrote:Would the current deformity be sufficient to cause a shifting in the rotational axis and force the buldge to rest at the equater?

I am doubting that BMA, but there are a couple of interesting ideas coming out.

But, I will still go with the idea that this is a destroyed space construct that has leaked it's atmosphere out onto it's surface.

That's my story, and it's sticking to me.

by **BMAONE23** » Sat Oct 13, 2007 2:05 pm

Would the current deformity be sufficient to cause a shifting in the rotational axis and force the buldge to rest at the equater?

by **geckzilla** » Sat Oct 13, 2007 2:09 am

How would you explain that it got split perfectly in half along the equator then? One would think that if it survived a large impact, it would be deformed a lot less uniformly. And how would something strike the moon without destroying it, instead "lodging" itself in the core? It doesn't exactly seem like a marshmallow to me. Although, the color is right on one side...

by **nateleavitt** » Sat Oct 13, 2007 12:58 am

How about another far-fetched theory ...

On object struck it with such force that it penetrated the surface and lodged itself somewhere near the core of the planet. Some core matter was ejected during the impact but the "Wound" closed up, sealing some magma and some air into the core of the planet. As the foreign body was "digested" and combined with the local material at the core of the planet, the existing air that was captured began to get superheated. Perhaps the mixture of the local magma and the new foreign material produced a gas. As the gas heated and expanded, the entire planet experienced tectonic shifting and adjustment. As the superheated gas pressure became too much for the core to contain, a giant bubble came out of the "wound" that was created upon initial impact. This carried magma with it and spewed it accross the surface of the planet. Then, with the sudden loss of pressure at the planet's core, the planet collapsed in upon itself, forming the ridge that now runs along the equator.

by **geckzilla** » Wed Oct 10, 2007 7:02 pm

Yeah Goove, I think this is the two things everyone is thinking:

Either somehow some crazy stuff flew out of the ridge, or it ran into a disc. It would have to have run into a disc or flat shaped object (or flat array of objects) for the stuff to have landed like that. I also have strange visions of a moon cracked in half and clapping together making a bunch of junk fly out but that sounds too crazy.

It probably ran into a disc.

by **Galactic Groove** » Wed Oct 10, 2007 6:24 pm

the mentioning of the north side slopes north of the equator and the south side slopes south of the equator being darker than their counters only holds true in the "transition zone." look away from this area and you'll see the craters fully dark or white (depending on which side of the transition you're looking at). If there was any evaporation taking place, then the entire white face of the moon would show greater signs of it, not just the slopes of the craters in this transition zone.

Also, is it 100% accurate that the dark side always trails like the caption says? if so, then it's all the more likely that the moon passed through some debris cloud or ring exactly like Danielallman is saying (and others). The slopes facing the debris as it went through would collect it while the slopes that didn't meet the debris head-on would collect very little.

If it did pass through a debris ring around Saturn, the craters in the white zone that are showing dark impacts would be more recent than this event since they didn't get the chance to be fully covered with the debris, if at all. The white peaks in the middle of these craters could still be in a position to collect the debris as it passed through since they are sticking out and more exposed unlike the surrounding valley below the peak which is protected by the crater walls. Simply because it's a depression in the main body of the moon, they are removed from this exposure to the debris.

by **Danielallman** » Wed Oct 10, 2007 3:03 pm

Looking at Iapetos' location is there no chance that it has almost "Scooped up" an older outer ring of Saturn?

by **geckzilla** » Wed Oct 10, 2007 1:29 pm

Maybe if there is some odd heat source hitting the moon in that direction or emanating from the ridge? I think they probably did some thermal imaging on it and any odd heat sources would have been detected though. IIRC, the dark areas were just all slightly warmer than the white areas with some slight variations and nothing else much worth mentioning. Shrug.

Today's APOD mentioned the ridge and the possible correlation between it and the dark stuff. Coincidence?

by **Vision** » Wed Oct 10, 2007 11:26 am

Thats no moon!!!

Nice catch andy.

by **auroradude** » Wed Oct 10, 2007 6:40 am

An example of what I am trying to get at was very noticable today. It was a clear blue sky day after a cold and clear night.
The temperature last night was in the high teens at our house near Homer, Alaska and it only got into the high thirties this afternoon. We had a hard frost this morning.
In the south-facing areas that the sun was hitting the frost thawed and evaporated leaving dark ground. In the shade, or north-facing areas the frost stayed all day leaving light ice-covered ground. This frost and frozen ground will most likely be around until the sun hits it again in the spring.

Couldn't the slopes of the craters of this moon with the dark deposits get more sun and turn even darker as the water ice evaporates? This water is then deposited as frost in places that recieve less sunlight making these colder areas lighter.
In the north the shadows fall on the north slopes and in the south the shadows fall on the south slopes. These would be light. Sunlight hits the south slopes in the north and the north slopes in the south. These would be dark.

by **geckzilla** » Wed Oct 10, 2007 4:06 am

I'm not quite sure what you mean, aurora.

by **auroradude** » Wed Oct 10, 2007 2:29 am

Yes, it seems to be split along the equatorial ridge but south-facing slopes in the north and the north-facing slopes in the south would also be explained by this evaporation process as these slopes would get more sunlight than opposite slopes and would therefore release the water vapor and become darker. The opposite slopes that recieve less sunlight would attract this water vapor as frost and become lighter.
Did I mention two processes earlier?

by **geckzilla** » Tue Oct 09, 2007 9:54 pm

It's odd that they don't mention that, even to decide to dismiss it as coincidence.

by **BMAONE23** » Tue Oct 09, 2007 9:52 pm

I know what you mean.

Not so much as a cause but in the effect of dark dust distribution.

All the dark material is covering areas that point to a traveling direction away from the equitorial ridge.
All dark material that is covering crater walls that lie north of the equatorial ridge tend to be covering the north walls of the craters, and all dark material south of the equatorial ridge is covering the south walls of the craters. While material covering equitorial craters tends to be more evenly distributed at the bottom of those craters.

by **geckzilla** » Tue Oct 09, 2007 9:45 pm

Interesting. The article mentions both the dark substance and the ridge but does not suggest any relation between the two. I'm a little disappointed.

by **JohnD** » Tue Oct 09, 2007 9:06 pm

The ESA site has just posted a long piece on the lastest images and opinion from the Cassini project. That is that the surface is black-on-white and not the other, and that the black, heat absorbtive surface is driving a process of 'thermal segregation' to exagerrate the contrast.

See: http://www.esa.int/SPECIALS/Cassini-Huy ... D7F_0.html

John

by **craterchains** » Mon Oct 01, 2007 9:07 am

by **Doum** » Fri Sep 21, 2007 2:04 am

now with all those last post i'm wondering if we have enter the twilight spam zone?

by **geckzilla** » Thu Sep 20, 2007 7:06 pm

You forgot the lens flare, John. Everything in space has a lens flare before it explodes in a fiery inferno.

by **JohnD** » Thu Sep 20, 2007 5:56 pm

A Thousand Curses!
You have penetrated my disguise.
Cower, Earthlings, before the might of my Intergalactic Paint Gun.

Jong the Magnificent

[/img]

by **BMAONE23** » Thu Sep 20, 2007 4:53 pm

JohnD wrote:...........

John

PS If I may be allowed my obsession as craterchains is allowed his (hers?), what sort of interplanetary war involves paint fights?

Haven't you ever played Paint Ball????

by **geckzilla** » Thu Sep 20, 2007 3:40 pm

Your bio states that you are 55. craterchains, do aliens periodically abduct some of your punctuation keys and then return them to you mid-sentence at times? Seems as though this would be a likely explanation for your use of commas in the beginning and ending of sentences rather than the usual punctuation.

Starship Asterisk*

Iapetus, WHITE on BLACK (APOD 19 Sep 2007)

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Iapetus shape and composition theory