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Re: Ice Age

HI,
I will take a stab at #4.

From Misner Thorne and Wheeler's "Gravitation" p
1113

The shift of the perihelion of Mercury

Total observed 5599.74"

From not being in "right" inertia frame
5025.6"

Newtonian from other planets
531.5"
General relativity
42"


One might think that the other planets being
beyond mercury would not have any effect, because
we often here that spherical shells beyond the
point of interest do not contribute
gravitationally. But the other planets are not
spherical shells about the sun. If I recall
correctly, they were treated as rings with mass
equal to the that of the planet and with a radius
the same as the radius of the planet's orbit. I
am amazed that in the 1910's the large Newtonian
contribution to the precession was calculated so
well that a 10% disagreement was well known and
accepted.

For planets other than mercury, I believe the GR
effects drop off very quickly.



The precession of the Equinoxes is 25800 years
and is caused by the precession of the earth's
axis (Unsold's " The New Cosmos" p15,16,46)
There is also a 19 year nutation and a 433 day
anomaly( shift of spin axis relative to the
surface of the earth). The overall precession is
related to the interaction of the earth's bulge
with the moon and sun.


Thanks
Roger Haar


****************************************************************************
Jim Green wrote:

A few questions: I am trying to evaluate a posting elsewhere re the causes
of a glaciation: Pick a question or two and enjoy:

1) What is the precession period of the Earth's spin axis?

2) What is the "Precession of the Equinoxes"? Is there is difference from
the above?

3) What would cause a periodic change in the eccentricity of the Earth's
elliptical orbit?

4) Please review why the orbit precesses: GR is needed here as I
recall. I assume that the orbits of all the planets precess as well as
that of Mercury.

5) Who is Milutin Milankovich?

TX

Jim Green
mailto:JMGreen@sisna.com
http://users.sisna.com/jmgreen