|Earth bulges at equator, flattens at poles
ABC ONLINE 7/8/2002
The earth bulges more at the equator and is flatter at both the North and South Poles
because of modifications in its gravitational pull, NASA has found.
It based its information on image data collected by the Topex/Poseidon satellite.
The researchers who operated the French-US ocean-observing satellite suggest that the
gravitational pull of the ocean itself could be responsible for changing the overall shape
of the earth.
Before 1998, the bulge at the equator seemed to be shrinking due to glacial shifts at the
end of the last ice age.
"Whereas the rebound had been decreasing the bulge in the earth's gravity field at
the equator, this recent phenomena is causing the bulge to increase," Christopher
Cox, a research scientist at the US space agency's Goddard Space Flight Centre in
Greenbelt, Maryland, said.
"The earth behaved much like putting your finger into a sponge ball and watching it
slowly bounce back," he said.
Scientists suggest that shifts in the ocean tides, moving water from one pocket to
another, are the most likely culprits for the change in the earth's shape, as bodies of
water move closer to the equator.