\(formerly\)" dlzc1.cox@net wrote in message news:rejXa.994$2g.194@fed1read05...
Dear Old Physics:
"Old Physics" wrote in message
om...
\(formerly\)" dlzc1.cox@net wrote in message
news:7m1Xa.847$2g.463@fed1read05...
...
msds means?
Mean solar days. 27.5 msds lose about 630s per MYr, the moon
Lunar siderial period losses about 400s for a difference of about
230s/MYrs.
Thanks for the clarification.
...
If you did a Neptune (I think it is), and aimed a pole at the Sun, most
of
the planet would be cold.
Actually it's the seventh planet, Herschel after its discoverer or
George the name he gave it. Uranus leads to too many klingon jokes.
Thanks again!
...
In this case I am putting the egg before the chicken. I hold
that
it was the change in the rate of transfer of angular momentum that
caused the earth's axis to increase its tilt and bring on severe
winters.
You'd have to change what we "know" about the mechanism of angular
momentum
transfer. If the planet's water is frozen, the tides won't transfer
much
momentum. I don't see how "lack of momentum transfer" can back
propagate
and freeze the planet.
I don't think all the water was frozen. The only thing I am
suggesting is that at these times the earth's magnetic field began
reversing, the equator rose relative to the poles and the earth got
cold because the axis went from no mor than five degrees off the
ecliptic to more than twenty.
The Moon does not have its own magnetic field. So momentum transfer to it
would be against whatever paramagnetism ir represents. And this would
mostly affect its spin (I think) and not its orbit. It is tides and tides
alone that drive this transfer from the Earth to the Moon. Now if they had
the same net non-zero charge...
You might want to review "tidal rhythmites" for additional background
on
length of year, length of day, length of month for up to 1 Gy.
Thanks for the tip.
Snow at the poles dosn't melt in summer and the reflected
light reduces the global temperature. This is why crocodiles no
longer swim in the polar sea.
I thought if might be because they got tired of getting snow in their
snorkels! ;}
They are reptiles, and have poor control of their body temperature.
Also,
there is not a whole lot of life at the poles, at least land-based
life.
But there was untill about 65 MYrs ago.
But this may only mean that it was NOT at the pole then. The net
rotational momentum of the Earth-Moon system may be "constant", but that
doesn't mean the Earth always spins around the same real estate. Look at
all the "crap" piled up near New Zealand's subduction zone.
Most of Canada is a "craton", it has been stable at the same
latitude for atleast 500 million years. The Champosaur (relative of
the crocodile) was found near what is now the artic circle, the temp
would have been about 60F year round. Evidence is that the whole
earth went down in temperature by atleast 15 degrees.
How does this correspond to the Solar System's periodic egress from
the
plane of the ecliptic of the Milky Way?
I've heard that used as a reason for extinction, like a change in
solar output. What is the periodicity?
http://physics.gmu.edu/classinfo/ast...t/ch20_txt.htm
20.3.3 ..."two or three times per orbit" ..."variation is probably not
more
than 1000 ly"
20.2.4 ..."revolution period of the Sun and the solar neighborhood (230
million years)"
An event that is repeated 2 to 6 times (depending on interpretation of
cycle) would be 38 to as much as 115 million years between "maxima".
Be
interesting if we encounter alterations in some physical "laws" as we
depart from the midplane. Alterations in the bond angles of water,
changes
in nominal emissivities/absorptivities, or perhaps encounters with DM
and/or DE altering the rate at which the Sun releases energy (or that
survives to be absorbed by the Earth).
Far to long to account for Heinrich events that occur with a
periodicity of about 13000 yrs, half a precession cycle. If it were
180 to 184 Myrs orbital resonance theory of mass extinctions would
have serious competition.
Agreed.
David A. Smith
Thanks again, David, sk