Path: ...!eternal-september.org!feeder2.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Jim Pennino Newsgroups: sci.physics Subject: Re: Europa and energy transfer Date: Thu, 31 Oct 2024 17:24:59 -0700 Organization: A noiseless patient Spider Lines: 77 Message-ID: References: <59851aac1a7edb0b9d9ddab7cdf8eb09@www.novabbs.com> <56e0f0368b32ee505901d6b19a26e7fe@www.novabbs.com> <5485db0fbdb51a017b1089635dadbd26@www.novabbs.com> Injection-Date: Fri, 01 Nov 2024 01:31:04 +0100 (CET) Injection-Info: dont-email.me; posting-host="da981c24dd04c14841f6f5085747343c"; logging-data="3073695"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1++tYOPzQqbaz1yWTl/A8Q9" User-Agent: tin/2.6.2-20220130 ("Convalmore") (Linux/5.15.0-124-lowlatency (x86_64)) Cancel-Lock: sha1:EZ01rELo13XcZEUOpK5fPU4EQPk= Bytes: 4188 bertietaylor wrote: > On Thu, 31 Oct 2024 14:27:05 +0000, Jim Pennino wrote: > >> Bertietaylor wrote: >>> On Thu, 31 Oct 2024 0:27:40 +0000, Jim Pennino wrote: >>> >>>> bertietaylor wrote: >>>>> On Wed, 30 Oct 2024 22:05:55 +0000, x wrote: >>>>> >>>>>> On 10/29/24 21:53, Sylvia Else wrote: >>>>>>> NASA has a mission to the Jovian system, to study Europa. That moon is >>>>>>> interesting because it appears to have liquid water under an icy >>>>>>> surface. The heat need to keep the water liquid comes from the >>>>>>> stretching and compression Europa experiences during its orbit around >>>>>>> Jupiter, the orbit not been exactly circular. >>>>>>> >>>>>>> So much, so simple. >>>>>>> >>>>>>> Some thought made me realise that although the tidal forces on Europa >>>>>>> mean that it is not exactly spherical, its two bulges cannot remain >>>>>>> perfectly aligned with Jupiter, because Europa's angular velocity >>>>>>> relative to Jupiter is higher at periapsis than at apoapsis. The result >>>>>>> is that the nearer bulge is sometimes ahead, and sometimes behind, >>>>>>> relative to Europa's orbital motion, resulting in a net force backwards >>>>>>> along the orbit, or forward along the orbit. >>>>>>> >>>>>>> Again, certainly stuff that's already well known. >>>>>>> >>>>>>> As far as I can see, the energy that is being dissipated as heat inside >>>>>>> Europa has to come from changes to Europa's orbit. Further, if Europa >>>>>>> were either perfectly rigid, or perfectly elastic, there would be no >>>>>>> energy transfer, and consequently no change to the orbit. >>>>>>> >>>>>>> It would make no difference if Jupiter itself were perfectly rigid, so >>>>>>> the transfer cannot involve tides on Jupiter generated by Europa. >>>>>>> >>>>>>> So the existence of the orbital energy transfer depends on Europa being >>>>>>> neither perfectly rigid nor perfectly elastic. >>>>>>> >>>>>>> What escapes me is the mechanism. >>>>>>> >>>>>>> Any thoughts? >>>>>> >>>>>> I am thinking that the standard model for Earth is that supposedly >>>>>> in the 1800s Lord Kelvin did some calculations. >>>>> >>>>> At that time they had thought the universe was only full of stars. >>>> >>>> Utter nonsense yet again, crackpot. >>>> >>>> By 1600 astronmers were well aware of different types of celestial >>>> bodies and beginning to measure distances to such. >>> >>> Did they have a clue about galaxies. >> >> "They" had a clue as early as 450 BCE crackpot. > > No, fool. > They thought the stars were the lights from Heaven. No, not everyone thought that crackpot. >> >> The first attempts at measuring distant objects where made around 1000 >> CE crackpot. >> >> The invention of the telescope in 1610 rather clinched the deal >> crackpot. > > Penisnino, all they found then that crystal spheres MAY NOT exist and > the Earth MIGHT go around the Sun. Utterly wrong crackpot.