The Earth is smaller than assumed: German researchers

Jul 05, 2007
Earth
German researchers at the University of Bonn said that the world is smaller than first thought.

Although the discrepancy is not large, it is significant: Geodesists from the University of Bonn have remeasured the size of the Earth in a long lasting international cooperation project. The blue planet is accordingly some millimeters smaller than previously assumed.

The results are important, for example, to be able to demonstrate a climate contingent rise in sea level. The results have now appeared in the renowned Journal of Geodesy.

The system of measurement used by the Bonn Geodesists is invisible. It consists of radiowaves that are transmitted into space from punctiform sources, the so-called Quasars. A network of more than 70 radio telescopes worldwide receives these waves. Because the gaging stations are so far apart from each other, the radio signals are received with a slight time-lag.

"From this difference we can measure the distance betwen the radio telescopes—and to the preciseness of two millimeters per 1,000 kilometers ", explained Dr. Axel Nothnagel, reasearch group leader for the Geodesy Institute of the University of Bonn.

The procedure is called VLBI, which stands for "Very Long Baseline Interferometry". The technique can be used, for example, to demonstrate that Europe and North America are distancing from each other at a rate of about 18 millimeters annually. The distance of the gaging stations from each other allows the the size of the Earth or the exact location of the center of the Earth to be determined.

"We have analyzed the measurements and calculations from 34 partners in 17 countries",explained Nothnagel. "A combination of GPS and satellite laser measurements will enable the availability of the coordinates from almost 400 points on the surface of the Earth with unparalleled exactness."

The results are the basis for a new coordinate system for the planet. With this system it would be possible, for example, to determine the track of so-called Altimeter-Satellites within a few millimeters precision. Altimeter-Satellites measure their altitude over the Earth’s surface and can, for example, register a rise in sea level. Deviations from the flight path, however, falsify the result. If the satellite flies higher than expected, the distance to the surface of the Earth differentiates from what is recorded—the sea level appears lower than it really is.

Source: University of Bonn

Explore further: How productive are the ore factories in the deep sea?

add to favorites email to friend print save as pdf

Related Stories

Detecting diamonds with X-ray technology

Apr 02, 2014

X-rays penetrate objects and reveal information about its contents. Using two X-ray spectra, you can identify different materials. And now, a new algorithm is making it possible to find diamonds in the rock.

Surface of Titan Sea is mirror smooth, scientists find

Mar 20, 2014

New radar measurements of an enormous sea on Titan offer insights into the weather patterns and landscape composition of the Saturnian moon. The measurements, made in 2013 by NASA's Cassini spacecraft, reveal ...

Recommended for you

How productive are the ore factories in the deep sea?

14 hours ago

About ten years after the first moon landing, scientists on earth made a discovery that proved that our home planet still holds a lot of surprises in store for us. Looking through the portholes of the submersible ...

NASA image: Volcanoes in Guatemala

19 hours ago

This photo of volcanoes in Guatemala was taken from NASA's C-20A aircraft during a four-week Earth science radar imaging mission deployment over Central and South America. The conical volcano in the center ...

User comments : 0

More news stories

Untangling Brazil's controversial new forest code

Approved in 2012, Brazil's new Forest Code has few admirers. Agricultural interests argue that it threatens the livelihoods of farmers. Environmentalists counter that it imperils millions of hectares of forest, ...

Study links California drought to global warming

While researchers have sometimes connected weather extremes to man-made global warming, usually it is not done in real time. Now a study is asserting a link between climate change and both the intensifying California drought ...

Genetic code of the deadly tsetse fly unraveled

Mining the genome of the disease-transmitting tsetse fly, researchers have revealed the genetic adaptions that allow it to have such unique biology and transmit disease to both humans and animals.