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SAB Collage: Self seeded trees and hill / Lochan / Lochan / Summit / view from N end down a dry stone wall / cairn / view east / Lochan again / view to main summit / Lochan from outlet

The results suggest that small celestial bodies like the Moon may retain internal heat longer than previously thought, contributing to updated models of the Moon's thermal history.

It's long been believed—since volcanism on Mars' appears to have faded perhaps hundreds of millions of years back, as well as Mars' lack of a planetary magnetic field, plus (intuitively) due to Mars' smaller size—that the martian interior must have cooled off to a much greater extent, not to speak of far faster, than Earth's. Thus, a hypothetical martian nickel-iron core (much like Earth's in the beginning) must (according to this line of thought) have frozen into immobility ages ago—eliminating the kind of liquid-iron, circulating dynamo now occurring in Earth's deep interior (in its outer core), thereby generating the terrestrial magnetic field. Such a hypothetically frozen iron core would appear to well explain Mars' lack of a planetary magnetic field. I saw this notion expressed recently as “Mars is dead, baby.” But as happens to so many fond suppositions—wrong! Recent results (October 2023) from analysis of signals from the (now defunct) Insight lander's seismograph (the only one thus far on Mars) reveals that—contrary to prior myth making—far from it being too cold, the Red Planet's interior is still _too hot_ to support a planetary magnetic field! One might note in this regard that Earth's magnetic field is produced by—its dynamo of circulating liquid-iron currents flows because of—energy released as our planet's _molten_ (iron-nickel) _outer_ core gradually _freezes_ onto its _solid_ (iron-nickel) _inner_ core. But Mars, we now know, is different. Its entire iron-nickel core is still completely _molten_ (together with the lower part of the rocky mantle above!) at this time. There _is_ no solid inner-core (yet!) for the (one and only) core's molten iron-nickel to freeze onto. As a result Mars lacks—for now—a planetary magnetic field. But as the podcast below points out, Mars may obtain one someday—as the martian core continues to cool and an inner core starts to solidify—in the future! ____

See this podcast from the journal _Nature_, from October 2023, for more information: https://nature.com/articles/d41586-023-03388-6…

And this journal article also from _Nature_: https://nature.com/articles/s41586-023-06586-4…

____ pics: 1) Graphic of Mars' interior: white=molten nickel-iron core, yellow=molten lower mantle; red=semi-solid mid mantle; black=solid upper mantle and crust. 2) Schematic of Mars' interior: “Ray paths for LSL- and core-interacting phases: P wave and S wave reflected from the top of the LSL (grey layer) (PdP and SdS), P wave diffracted around the mantle–LSL interface (P LSL/diff), P wave reflected from the liquid core (PDcDP), P wave diffracted around the LSL–liquid core interface (P CMB/diff) and reverberating in the LSL (Pdiff LSL Pdiff), and liquid-layer and core-transiting P wave (SDKDS).” [Ref. 2]