Scientists introduce cosmochemical model for Pluto formation

Phys dot org ^ | May 23, 2018 | Southwest Research Institute

[SunkenCiv]

Southwest Research Institute scientists integrated NASA's New Horizons discoveries with data from ESA's Rosetta mission to develop a new theory about how Pluto may have formed at the edge of our solar system.

"We've developed what we call 'the giant comet' cosmochemical model of Pluto formation," said Dr. Christopher Glein of SwRI's Space Science and Engineering Division. The research is described in a paper published online today in Icarus. At the heart of the research is the nitrogen-rich ice in Sputnik Planitia, a large glacier that forms the left lobe of the bright Tombaugh Regio feature on Pluto's surface. "We found an intriguing consistency between the estimated amount of nitrogen inside the glacier and the amount that would be expected if Pluto was formed by the agglomeration of roughly a billion comets or other Kuiper Belt objects similar in chemical composition to 67P, the comet explored by Rosetta."

In addition to the comet model, scientists also investigated a solar model, with Pluto forming from very cold ices that would have had a chemical composition that more closely matches that of the Sun.

Scientists needed to understand not only the nitrogen present at Pluto now—in its atmosphere and in glaciers—but also how much of the volatile element potentially could have leaked out of the atmosphere and into space over the eons. They then needed to reconcile the proportion of carbon monoxide to nitrogen to get a more complete picture. Ultimately, the low abundance of carbon monoxide at Pluto points to burial in surface ices or to destruction from liquid water.

"Our research suggests that Pluto's initial chemical makeup, inherited from cometary building blocks, was chemically modified by liquid water, perhaps even in a subsurface ocean," Glein said.

[P.O.E.]

Rick & Morty cartoon about Pluto

[SunkenCiv]

The four rocky planets -- Mercury, Venus, Earth, and Mars -- obviously formed differently from the gas giants -- Jupiter, Saturn, Neptune, and Uranus -- hence, there is no astrophysical reasoning behind it, and as you said, more will be discovered, so why the rush? The ONLY reason for the reclassification was the blind panic over US planetary discoveries. Mike Brown, who agrees that Pluto "had to die", but who was thus denied discovery of a tenth planet, also saw the creep from Spain get off without censure or any other symbolic punishment for hacking and stealing Brown's research. Obviously the hacking and stealing was a real issue that should have been dealt with, and was ignored instead.

[Telepathic Intruder]

Actually the inner rocky planets formed similarly to the outer gas ones except that the inner ones were close enough to the sun for most of their lighter material—hydrogen and helium—to be forced outward during the sun’s T-Tauri phase of high solar winds. Otherwise, they all formed as small planetesimals coalescing into larger ones until there was no more raw material in their general orbits. There are regions of instability, however, where this process remained incomplete. Namely the asteroid belt and the later discovered Kuiper belt, of which Pluto is part.

Personally I’m not particularly worried about what “defines” a planet. Naming conventions are by nature often ambiguous to a degree, resulting in exceptions to the rule. There is no real difference between a mountain and a hill, for example, except some arbitrary height from base to summit. Originally, the term “planet” referred to a star that wanders instead of remains fixed. So under that definition, the earth isn’t even a planet.

[SunkenCiv]

Thanks, the similarity of the process is what you obviously see, just have some problem with the materials used. There's no more reason to separate Pluto and planets further out than there is to separate the gas giants from the terrestrial planets.