“Surprise” or “puzzling” are the most common words in news reports about bodies in the solar system. Here are recent examples that discuss the outer planets.
Jupiter: role in Earth habitability: Elizabeth Howell talks in Space Daily about mathematical models that show what happens when Jupiter is repositioned in the solar system. Before exoplanets were confirmed in the 1990s, astronomers had expected other planetary systems to resemble ours. Then, the discovery of “hot Jupiters” around many stars showed that our planetary system is the exception. What role does the position of a gas giant play in habitability of rocky planets? It’s an ongoing work, because in some models not much happens, but in others it dramatically affects Earth’s climate. Australian astrobiologist Jonti Horner indicated that Earth is in a delicate position: “He added that the new research underscores how a small change in parameters could change habitability wildly,” Howell wrote.
Saturn ring moons: Astrobiology Magazine celebrated an announcement by Cassini scientists who found a large clump of material in the outer A-ring, which some think could be a moon forming. They think it “may be a new moon, and may also provide clues to the formation of the planet’s known moons.” Based on the evidence, though, such celebrations seem more hype than reality:
The object is not expected to grow any larger, and may even be falling apart. But the process of its formation and outward movement aids in our understanding of how Saturn’s icy moons, including the cloud-wrapped Titan and ocean-holding Enceladus, may have formed in more massive rings long ago. It also provides insight into how Earth and other planets in our solar system may have formed and migrated away from our star, the sun.
That’s a lot of hope to pin on a clump that may vanish in the next few rotations, but optimistic scientists even gave it a name: Peggy. Yet the Cassini scientists admit the rings are too depleted to form moons today. Only by imagining thicker rings in the past can they imagine how Saturn’s moon family formed – but that, then, begs the question of how the short-lived rings formed in the first place.
Saturn’s Enceladus: imaginary cooking episodes: A paper in Icarus, the planetary science journal, tackles the problem of the active moon Enceladus. Only by modeling unobserved cyclic heating episodes in the past can they explain the geysers today. “It is largely probable that the activity of Enceladus is not in a steady state,” they say, but that probability is based on the belief Enceladus is billions of years old. Even their own model, which tweaks various parameters, cannot account for the current tidal heating. The guesswork multiplies as they wave possibilities in the air:
The duration of one episodic heating cycle [in their model] is around one hundred million years. The cyclic change in ice thickness is consistent with the origin of a partial ocean which is suggested by plume emissions and diverse surface states of Enceladus. Although the obtained tidal heating rate is smaller than the observed heat flux of a few giga watt, other heating mechanisms involving e.g., liquid water and/or specific chemical reactions may be initiated by the formation of a partial or global subsurface ocean.
How would one ever run experiments on that?
Saturn’s Titan: The Wave: Papers are contradicting each other about wind waves on Titan’s lakes. While a press release from Stanford University claims the lake surface of Ligeia Mare is mirror smooth (ripples < 1 mm), Nature News announced at about the same time that ripples (< 2 cm) were possibly found on Punga Mare, another lake in the northern hemisphere. That’s still pretty flat. Astrobiology Magazine can’t decide which observation (based on infrared and radio measurements, respectively) is more correct. Whether wind conditions will change as the giant gas-robed moon approaches solstice remains to be seen. Other possibilities could be that the liquid is viscous, like tar, or the lakes are more shallow than believed, like mudflats. “There is still a chance that Cassini is seeing reflections off a wet, solid surface, such as a mudflat, rather than actual waves,” Nature admits. If so, the amount of liquid on Titan’s surface is far, far less than earlier predicted based on calculations of ethane buildup over billions of years, which should have produced a global ocean of ethane up to several kilometers deep.
Saturn’s Iapetus: Ring collapse? It would be a bad day on Iapetus when its ring collapsed and rained down to the surface, building an equatorial mountain range 12 miles high. That’s what a new paper on Cornell’s arXiv server, referenced by PhysOrg, is proposing. They base their idea primarily on the triangular shape of the ridge profiles. They don’t say when it occurred, how it occurred, or what caused it to occur. “Iapetus is among the most unusual planetary bodies in the Solar System,” they say in conclusion, emphasizing plausibility over causality. “Although the formation of its equatorial ridge remains mysterious, the most common triangular ridge morphology and the evidence of slope angles close to the angle of repose make the case for an exogenic origin more plausible.” PhysOrg, however, invoked scientists’ favorite mechanism for solving any problem: an impact. “A ring around the moon would most likely have come about due to a collision, either between another body and the moon, or two other bodies nearby.”
Pluto: ring collapse too? Speaking of fallen rings, Pluto’s darker equator may have resulted from dust buildup over 3.5 billion years, New Scientist says (why the first billion years was not mentioned is unexplained). While dust would fly off its smaller moons, presumably, Pluto has enough mass to keep its infalling dirt. William McKinnon (Washington University, St. Louis) doubts that Pluto is a dust vacuum like Iapetus. “I think Pluto is a very active place, with an atmosphere and frosts that come and go,” he said. Since observations are difficult at its distance, confirmation of what’s happening will await the arrival of the New Horizons spacecraft a year from July.
Constant comets: It’s rare to see an exclamation point in the title of a scientific paper. Here’s one on Icarus: “Comets formed in solar-nebula instabilities! – An experimental and modeling attempt to relate the activity of comets to their formation process” (paper available for download on Cornell arXiv server). The authors believe they have confirmed a maverick hypothesis of comet formation by Skorov and Blum (2012), “who assumed that cometesimals formed by gravitational instability of a cloud of dust and ice aggregates.” Since traditional theories would form dust layers with too much tensile strength to allow volatiles to sublimate through them, these authors believe Skorov and Blum have a working model (note: Blum is one of the co-authors of the new paper).
In the paper, they struggle with the difficulties of getting comets to form up to sufficient size to attract more particles and avoid erosion. Both models require fairly rapid formation—a few thousands of years. Another problem is getting refractory minerals (formed at high temperatures) to mix with volatile ices in the Oort Cloud and Kuiper Belt regions. They must have mixed in the nebula, they reason, to have been detected near the surface of Comet Wild-2 by the Stardust spacecraft. Sample quote:
As to the formation timescales for cometesimals, these are required to be long enough for the radial mixing of the high-temperature condensates to occur, but certainly shorter that [sic] the lifetime of the nebula gas. As this might be a problem for the MT [mass transfer, or accretion] origin of cometesimals at large heliocentric distances, the timescales for the instability-driven formation of cometesimals should always be sufficiently short. In the latter, however, the aggregate sizes at which the bouncing barrier is reached and for which then some concentration process forms a gravitationally unstable cloud, could be considerably different (albeit yet unknown) for the two reservoirs of Kuiper-belt and Oort-cloud comets.
The “bouncing barrier” refers to the observational fact that particles tend to bounce off each other and fragment until they reach sufficient size to have enough gravity to attract more particles than they lose. As they state, whatever “some concentration process” is that drives the growth of comets is “albeit yet unknown” despite their bang (!) in the title.
We hope you are enjoying watching secular astronomers squirm as their theories collide with the facts. Yet they want to invoke collisions everywhere to bring order out of chaos! Why don’t we try that with computers? Bang some silicon atoms around and see what happens. As NASA showed in a stunning video (2/09/14 entry), the Earth is a finely-tuned machine with multiple factors that make it habitable. Beyond the Earth, none of the planets or moons of the solar system follow any scientific formation law that would allow a “scientist” to make predictions: e.g., “given a moon with such-and-such a surface composition and density, it will have volcanoes or geysers.” One needs that kind of bold predictive power to do science. Instead, every body appears unique and surprising. Most of the puzzling surprises would evaporate without the requirement of billions of years. The others would evaporate without the requirement of secular naturalism.
In Part III we will evaluate recent articles about theories of planet formation.