August 16, 2011
New Study Shows Earth Is Staying The Same Size
NASA has put to rest any speculations that Earth maybe expanding or contracting.
New research has found that there has been no statistically significant expansion of the solid Earth.
Tectonic forces like earthquakes and volcanoes push mountains higher, while erosion and landslides wear them down, helping to change the Earth's shape.
However, despite the facelift, this new research - using space measurement tools and a new data calculation technique - says Earth's size will remain the same.
Researchers referenced their measurements against the International Terrestrial Reference Frame established by the global science community.
This reference frame is used for ground navigation and for tracking spacecraft in Earth orbit. It is also used to help monitor many aspects of global climate change, sea level rise, imbalances in ice mass at Earth's poles, and other research.
The field of high-precision space geodesy allows scientists to estimate changes in the Earth's radius. These tools include: satellite laser ranging, very-long baseline interferometry, Global Position System and Doppler Orbitography and Radiopositioning Integrated by Satellite.
The international group of scientists led by Xiaoping Wu of NASA's Jet Propulsion Laboratory set out to independently evaluate the accuracy of the International Terrestrial Reference Frame and shed new light on the Earth expansion and contraction theory.
NASA said the team applied a new data calculation technique to estimate the rate of change in the solid Earth's average radius over time, taking into account the effects of other geophysical processes.
The techniques were used to obtain data on Earth surface movements from a global network of selected sites. These data were then combined with measurements of Earth's gravity from NASA's Gravity Recovery and Climate Experiment (GRACE) spacecraft and models of ocean bottom pressure.
They found that the average change in Earth's radius is to be 0.004 inches per year, or about the thickness of a human hair. According to NASA, this rate is considered to be statistically insignificant.
"Our study provides an independent confirmation that the solid Earth is not getting larger at present, within current measurement uncertainties," Wu said in a press release.
The NASA study was published in Geophysical Research Letters.
Image Caption: This view of Earth comes from NASA's Moderate Resolution Imaging Spectroradiometer aboard the Terra satellite. Image credit: NASA
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