Curvature of earth.

[AntarcticPilot]

You say this with such certainty - but then, it's a better explanation than 'Genesis, Chapter 1'.

Now - about these comets ....

Most of the water on earth came from the planetesimals from which the Earth (and other planets) formed. Comets probably have a similar composition to the primordial planetesimals, but are unlikely to be a major source of water; the Earth isn't gravitationally attractive enough to be struck by large numbers of them. The Earth happens to be large enough and cold enough to retain water; Venus and Mars probably have significant water, but in Venus' case it is combined with other minerals, and not present as liquid; Mars is small and has lost most of it.

The planetesimals that originally coalesced to form the earth probably had a lot more water proportionately than the earth does; Hydrogen and Oxygen are cosmically very abundant. The question is really "Where has the water gone?" not "Where did it come from?"

With another hat on, Genesis tells us a lot about God, but is not a text book on planetology.

 

[Momac]

Mathamaticians please. If we take a 100 miles span of sea, how far below the high (mid) point are the two ends?

If radius of earth; R=6371km

Circumference of spherical earth ; C=2xpixR=40030.174km

If length measured on curvature ;L=1.852kmx50=92.600km ; (50 nautical miles)

Angle turned; A=(L/C)x360degs=0.8327718071degs;

Apparent difference in level as viewed from a level datum at the current position;

Cos(A)=0.9998943744

; D= Rx(Cos(A))=6370.327km

R-D=672.941m

This applies ony if the line between the mid point and the ends of a line of travel follows the maximum circumference of the sphere - around the equator , or travelling due north or south for example. If the line of travel is say above the equator and you are travelling West or East your route around the sphere would be over a shorter circumference . So you would turn a greter number of degrees per mile and the apparent difference in elevation would be greater.


But this is an ''apparent'' difference in level from a level datum at the mid point which is at a tangent to the sphere. In fact the mid point and the ends are all at the same distance from the earths centre so all three points are at the same elevation.