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Re: Pull of the Moon



Excuse me but isn't this whole discussion a bit overblown? Current recession rate is ca 3,8 cmyr-1, average rate over the Cenozoic is estimated at c. 2,2 cmyr-1. Admittedly the later figure may be in error, but the current rate is rock-solid (based on direct measurement on the laser reflectors left by Apollo astronauts on the Moon). We can also be reasonably sure that the current tidal dissipation figure *is* higher than the long-time average based on the current continental distribution, with three north-south barriers stretching almost from pole to pole (The Americas, Europe-Africa, East Asia - Indonesia - Australia).

However even if we extrapolate the current high rate back to the Mid-Cretaceous (100 Mya ago) we get 3,8 x 10^-2 x 10^8 = 3,8 x 10^6 meters, i e about 4,000 kilometers. That is about 1% of the Moons current distance. I strongly doubt that this would be even noticeable to the unaided eye, except that annular solar eclipses would be rarer or maybe absent.

Incidentally we're only just in time to have total solar eclipses, in a few hundred million years it will be to late.....

Tommy Tyrberg






At 14:53 2006-04-19, frank bliss wrote:
Correct, the moon currently subtends an average of 30 minutes of
angle. (30 inches at 100 yards).  This is roughly equal to the sun
though the sun looks bigger.  1/4 larger in the Mesozoic would be
37.5 minutes of arc.  Subjectively not a huge difference but it would
be noticeable.  I think another brain degassification occurred with
1.25 being the multiplier not the product.  Two days of 40+ mph wind
(High wind of 54 last night with 5 inches of heavy snow) is taking
it's toll on the locals me included. It is a cold day in Hell Creek!

Frank (Rooster) Bliss
MS Biostratigraphy
Weston, Wyoming
Blizzard Waste Land



On Apr 19, 2006, at 5:43 AM, jrc wrote:

Wouldn't 1/4 larger have been 7.5 minutes of angle?


 Since the moon may have been 1/4 larger (ie. 1.25  minutes of
angle),