Re: Pull of the Moon

[Tommy Tyrberg <tommy.tyrberg@norrkoping.mail.telia.com>]

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),