Inventions and Deceptions – Earth’s Gravity Anomaly

Mainstream science currently has a very perverse predilection for reporting “anomalies” instead of reporting upon the “raw data”.

Unfortunately, this preference for “anomalies” has significant disadvantages for Science [and especially the consumers of science] because the “baseline” can be [arbitrarily] changed and the “raw data” is hidden from view so that it cannot be directly verified or analysed.

Therefore, the reporting of “anomalies” [by the mainstream] has to be consumed with extreme caution because “anomalies” are synonymous with obscuration, misdirection and political agendas.

The mainstream reporting of the Earth’s “gravity anomaly” is a classic example because the “raw data” is hidden and the “baseline” is arbitrarily defined by a “model”.

A gravity anomaly is the difference between the observed acceleration of a planet’s gravity and a value predicted from a model.

http://en.wikipedia.org/wiki/Gravity_anomaly

The theoretical gravity “baseline” is called the “geoid”.

The geoid, simply stated, is the shape that the surface of the oceans would take under the influence of gravity alone. All points on that surface have the same scalar potential – there is no difference in potential energy between any two. In that idealized situation, other influences such as winds due to solar heating, and tides have no effect. The surface of the geoid is farther away from the center of the earth where the gravity is weaker, and nearer where it is stronger. The differences in gravity, and hence the scalar potential field, arise from the uneven distribution of the density of matter in the earth.
Deviation of the Geoid from the idealized figure of the Earth
http://en.wikipedia.org/wiki/Geoid

Mainstream science is very happily [and gainfully] employed analysing the “geoid” and reporting upon gravity “anomalies”.

Goce satellite views Earth's gravity in high definition
Goce satellite views Earth’s gravity in high definition
http://news.bbc.co.uk/2/hi/science/nature/8767763.stm

Gravity anomaly map from the NASA's GRACE (Gravity Recovery And Climate Experiment)
Three-dimensional visualization of geoid undulations, using units of gravity.
http://en.wikipedia.org/wiki/Geoid

The Gravity Recovery And Climate Experiment (GRACE), a joint mission of NASA and the German Aerospace Center, has been making detailed measurements of Earth’s gravity field since its launch in March 2002.

Gravity is determined by mass. By measuring gravity, GRACE shows how mass is distributed around the planet and how it varies over time. Data from the GRACE satellites is an important tool for studying Earth’s ocean, geology, and climate.

Global_Gravity_Anomaly_Animation_over_LAND

Global Gravity Anomaly Animation over land from GRACE
http://en.wikipedia.org/wiki/Gravity_Recovery_and_Climate_Experiment

Global_Gravity_Anomaly_Animation_over_OCEANS

Global Gravity Anomaly Animation over oceans from GRACE
http://en.wikipedia.org/wiki/Gravity_Recovery_and_Climate_Experiment

Unsurprisingly, there is a dearth of mainstream reporting of actual gravity “raw data”.

However, the Western Australian Centre for Geodesy [Curtin University] appears to have reverse engineered [for comparison purposes] a map of the Earth’s surface gravity.

Variations of gravity accelerations over Earth's surface
Variations of gravity accelerations over Earth’s surface.
Azimuthal equidistant projection with a central meridian of 0° longitude (left) and 180° (right).
Map is based on data from EGM2008 (Pavlis et al., 2008)

http://geodesy.curtin.edu.au/research/models/

There are some very interesting features of this map of the Earth’s gravity accelerations:

1. Gravity is [evidently] a resultant “net” force where a [inward] centripetal force is partially offset be a tangential centrifugal force [which varies by latitude].

2. The lowest surface gravity on the planet is at the equator.
This appears to be counterintuitive [from a Newtonian perspective] because of the additional mass contained in the Earth’s “equatorial bulge”.

3. The highest surface gravity on the planet is at the poles.
This appears to be counterintuitive [from a Newtonian perspective] because the Earth’s oblate shape dictates that there is less mass at the poles [compared to the equator].

Harmonic shape model of the interface between Earth and its atmosphere
Harmonic shape model of the interface between Earth and its atmosphere, providing radii of the terrain and ice over land and of the sea level over the oceans.

http://geodesy.curtin.edu.au/research/models/Earth2012/

Perhaps, one day, the mainstream will publish some “real” satellite data [in the form of a surface gravity map] so that we can actually begin to analyse Earth’s gravity. I am not holding my breath.

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One Response to Inventions and Deceptions – Earth’s Gravity Anomaly

  1. After some discussion around here, point 2 above can be seen to match the notion that G works with respect to the center of the mass. In this case the poles are _closer_ to the center of the earth and hence have more acceleration. Now if one takes a thought experiment such that the earth is 10%, 20% or more flatter, in theory the acceleration at the pole would be stronger as the poles get closer to the center of mass. The limit where the earth is infinitely thin gravity would be at it maximum… Seems legit /sarc

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