Cassini

See Figure 1 of metaresearch.org/solar%20system/eph/eph2000.asp and its accompanying text. -|Tom|-

Regarding Iapetus:

There is a new article on space.com about Iapetus. The article can be found here:

[url] www.space.com/scienceastronomy/mystery_monday_040426.html [/url]

Here is an interesting quote from the article:

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">"Another surprise is that the radar system sees Iapetus as a uniform object, meaning no difference between the light and dark sides," Black said.

That could mean that on the dark side there is merely a thin coat of some darkening material over the ammonia-laden water ice, like an inch of dirt atop clean snow, Black said.

"A thin coating would not have much effect on the radar reflection, which sees the underlying ice, and therefore both sides would look the same in radar but differently optically," he said. "This interpretation depends somewhat on what the dark material is made of, but we are not able to answer that question."<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

The EPH predicts that just such a thin lyaer of dark material would be deposited on moons, such as Iapetus, that have slow rotation periods.


Tom,

Does the presence of this black material mean that Body C was black? Or was it scorched black?

--Astro

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Astrodelugeologist</i>
<br />Does the presence of this black material mean that Body C was black? Or was it scorched black?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">When a large body explodes in the solar system, much of it is vaporized into a huge, expanding blast wave. The contents of that blast wave are light-absorbing matter (i.e., very black). For example, the wave contains considerable soot, assuming that carbon was abundant in the body that exploded. So the blast wave is black, but the body that exploded was normally not black.

As the blast wave travels, it gets thicker because of differential speeds. It takes months to years to travel to other planets. During that time, the blast wave gets thick enough to take days to weeks to pass any distant planet.

When that wave collides with a cold, airless moon, the moon will get blackened on all parts facing the blast wave during the days to weeks it takes to pass. The predicted distribution of blast wave material from a major explosion is called the "black axiom". Because Iapetus takes 79 days to rotate once, it is an excellent candidate to show this blackening on only one side. And it would indeed be a thin black surface layer when deposited, just as these new radar observations show. One previous speculation for the cause of the blackened hemisphere was volcanic lava flows, which would likely change the radar reflectivity for the two hemispheres, contrary to observation.

Incidentally, I consider the "Planet V" (former parent body for both Mars and Body C) explosion at 65 Mya to be a more likely source for the black material than the Body C explosion at 3.2 Mya, despite the blackness of comets from the Body C event. I suspect this because Body C produced a much smaller blast wave and had a high water content. Moreover, we actually see the blast wave deposited on Earth in the form of a soot later at the K/T boundary, 65 Mya; yet do not see any appreciable soot layer at 3.2 Mya on Earth.

When I mentioned the black axiom to the late Carl Sagan 12 years ago in connection with Iapetus, he immediately came up with a challenge. The black hemisphere of Iapetus, Sagan said, was tilted by about 40 degrees out of the plane of the ecliptic, which apparently made an ecliptic-plane source unlikely. I had no answer for him on the spot. But I later looked up the tilt of Saturn's equator to the ecliptic: 27 degrees; and the tilt of the orbit of Iapetus to Saturn's equator: 15 degrees. Additionally, it is possible that the spin axis of Iapetus is inclined a few degrees to the plane of its own orbit. There are times when these three tilts are in phase and add up. At such times, Iapetus would be inclined by up to roughly 45 degrees to the plane of the ecliptic. That highly non-intuitive result explained "Sagan's paradox" for the black axiom. -|Tom|-

Tom,

What do you think of Saturn's moon Phoebe? It's backwards orbit seems to indicate that it was captured (though gravitational screen capture, perhaps?). It's also quite dark. But Phoebe is a somewhat different shade of black from the material coating Iapetus. Does that mean that it came from a different planetary explosion?

Also, is it possible to calculate the size and speed of the blast wave from the Planet V explosion, given the rotation rate of Iapetus and the amount of its surface that is covered with black material?

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Astrodelugeologist</i>
<br />What do you think of Saturn's moon Phoebe? It's backwards orbit seems to indicate that it was captured (though gravitational screen capture, perhaps?).<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Phoebe is too far out for gravitational screen capture. Accretion capture is indicated.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">It's also quite dark. But Phoebe is a somewhat different shade of black from the material coating Iapetus. Does that mean that it came from a different planetary explosion?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">My suspicion is that Phoebe is material directly from the exploded parent body, and is therefore intrinsically a black object. By contrast, Iapetus is an icy body overlaid with soot and blast wave debris. Because the debris layer is thin, the spectrum is a composite of intrinsic and overlaid materials.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Also, is it possible to calculate the size and speed of the blast wave from the Planet V explosion, given the rotation rate of Iapetus and the amount of its surface that is covered with black material?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">That technique will allow us to calculate the blast wave velocity dispersion, which represents the spread in arrival times. That is a different parameter than the velocity itself, which represents the travel time from explosion to Iapetus. -|Tom|-

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Phoebe is too far out for gravitational screen capture. Accretion capture is indicated.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

What is the maximum planet-moon distance at which one could logically conclude that a moon was captured through gravitational screen capture?

--Astro