Empirical Earth · Gravity, Buoyancy & the Air

The “spinning water ball”: oceans are a thin film

The claim

“Water can’t curve around or cling to a spinning ball.”

What is measured

Oceans average just 3.7 km deep on a 6,371 km radius, a layer about 0.06% of the radius and 0.02% of Earth’s mass. Gravity holds that film easily, and the spin cannot throw it off.

What would show this is wrong

a measurement showing Earth’s spin produces an outward acceleration comparable to gravity, or oceans whose mass is a large fraction of Earth’s total.

Sources

  1. NASA NSSDCA — Earth Fact Sheet. D. R. Williams, NASA Goddard Space Flight Center. nssdc.gsfc.nasa.gov/planetary/factsheet/earthfact.html link
  2. World Geodetic System 1984 (WGS 84). NGA Standardization Document, defining ellipsoid parameters (a, f, b). National Geospatial-Intelligence Agency. WGS 84 link
  3. Charette, M. A. & Smith, W. H. F., “The Volume of Earth’s Ocean,” Oceanography 23(2), 2010. Mean ocean depth 3,682 m; total ocean mass ~1.35×10²¹ kg, about 0.02% of Earth. Oceanography 23(2) link
  4. Earth’s equatorial bulge and the farthest summit from its center. Rotation makes Earth an oblate spheroid: mean sea level at the equator (6,378.1 km from the center) is about 21 km farther o link
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