Why is Earth's Girth Bulging?

August 7, 2002

This is heavy.

Something massive is moving on or within the Earth and causing the planet's gravity field to get wider around the equator and flatter at the poles, according to a pair of scientists studying the field with sensitive satellite instruments.

"Starting after 1997, the world that was getting rounder started getting more oblate [flattened at the poles]," said Christopher Cox, a research scientist at the Space Geodesy Branch of NASA's Goddard Space Flight Center in Greenbelt, Maryland.

"It has finally gotten so big that we can't explain it with any known mechanism," said Cox, who co-authored a paper in the August 2 issue of the journal Science on this change in shape of the Earth's gravity field.

[link to news.nationalgeographic.com]