Bad Astronomy and Universe Today Forum - View Single Post

tusenfem · #67 (**permalink**) 28-March-2008, 02:45 PM

Well, it looks like there are now two topics to be discusses, which are slightly linked. One is the history, the other is the (non)significance of the great Platonic year and its twelveths (darn, that is a difficult word) and the motion of the barycenter of the solar system.

Now, the precession of the Earth is 25,765 years, and can completely be described by the torque on the Earth from mainly the Sun and the Moon and for a lesser extend by other solar system bodies. Now, the question is: when periodicity of the barycenter of the solar system is 179 years to return to its starting point, would it not be reasonable that this periodicity is also in the Earth's precession? The ratio of these to periods is ~144 of which, naturally, the square root is 12. But what does this mean?

First of all, I would expect that the precession of the Earth might vary a little in period through the 179 year cycle, or will it?????? What does the barycenter describe? It is the center of mass of the solar system, and naturally this moves around because the planets have different locations all the time, but does that mean that the distance Earth-Sun changes? No, that remains fixed through the orbit of both. So, basically, I do not have any inclination, at the moment, to suspect that the motion of the barycenter has any influence on the torque that the Sun and Moon (and other bodies) provide on the Earth in order to make it precess. However, the two are related in the fact that both the total torque and the motion of the barycenter are generated by the solar system bodies.

This leaves the fact that the ratio of the two, precession and barycenter period, is just coincidentally 144.

The claim that: The precision of the correlation suggests physical causation, although its scientific basis needs more study and my numbers should be checked. does not hold, as I showed in another thread using some spurious correlation between the shirt I chose to wear that day and receiving an email. Only, when based on a real mechanism can correlation imply causation.

Also, the Earth is not "whipped like a gyroscope" by Jupiter or Saturn. As is well known (even wiki knows this!) the main reason for the Earth precession is the torque by the Sun and the Moon, as I already said above. I think Celestial Mechanics had one of his nice dialogues precisely on this topic.