September 13, 2016 Zimmerman/Batchelor podcast

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Embedded below the fold. Tonight was a special double podcast, lasting almost 40 minutes. The first segment looks at the September 1 SpaceX launchpad situation, the second segment looks at Blue Origin and its new proposed rocket, the third segment looks at the state of Virgin Galactic and the Russian space industry as well as the Mars rovers, and the last segment looks at Mars, the Moon, earthquakes, and the coming end of Rosetta.


  • Greg Jones


    Starting at roughly 37:25, you / Mr. Batchelor discussed how the Moon might possibly cause earthquakes at high (Earth) tides during new / full Moon phases. You basically said that based on tidal effects and the effects of gas giants on their own moons that the Moon might well influence earthquake activity. I’m wondering about the effect of the Earth on the Moon, if this might cause moonquakes.

    says that the Moon has 1.2% of Earth mass, so FWIW that differential is “fairly” large, but nothing like the Jupiter / Saturn / etc. systems, of course. The Moon has tidal locking, Earth does not, so the Moon does not rotate and therefore, its surface does not flex and would not heat the interior. Based on this, it looks like Earth does not cause moonquakes. Thoughts?


  • Greg Jones

    Sorry – the Moon obviously DOES rotate – just not relative to the Earth. They call that tidal locking!

  • Edward

    Greg Jones,
    Nice observation. I haven’t looked into this topic before, because the moon is fairly solid. It has a small liquid core (about 20% of the diameter) so plate tectonics is unlikely, thus no tidal effects. Thus the only moonquakes would be from meteorite impacts, right?

    But wait! I came across this tidbit on NASA’s site:
    There are at least four different kinds of moonquakes: (1) deep moonquakes about 700 km below the surface, probably caused by tides

    As you pointed out, Greg, the Moon does rotate, so the tides would be caused by the sun.

    Whether there is enough flexing to heat the interior is a mystery to me, but I would have said “no, obviously not” just a few minutes ago.

  • wayne

    Good show, always enjoy the longer-form! (the mp3 download only has the 1 intro-commercial, priceless!)

    Greg Jones/Edward–

    Fairly good read you might find of interest. Not a full-blown geology-techie text-book, but not dumbed down. (originally published 1995 with a revision in 2007)
    They cover all the Planets but you can only read chapter 4 for free on-line. (or I should say– I have the hard-copy ’95 edition. The online version is the 2007 revision, & I don’t think it’s available in its entirety for free but I haven’t looked.)

    “Exploring the Planets”
    Chapter 4: The Geology of the Moon

    (I wouldn’t be surprised that Gravity is having its way with all of us & everything!)

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