Shrinking Earth?

The Department of Earth and Planetary Sciences at the Ministry of Art & Jump, might think that Earth is shrinking! In Bonn, Germany, researchers revealed last summer that the planet is smaller than we thought. The last measurement was five years ago, and when the two measurements was compared – the difference is half a centimeter.

German scientists from the University of Bonn took part in an international project to measure the diameter of the world and came up with the 5 mm decrease. The scientists rounded the diameter of the Earth up to 12,756.274 kilometers (7,926.3812 miles) for the general public.

Though it may appear a trifling difference, Axel Nothnagel, who led the researchers, said the difference is crucial in the study of climate change. “It may seem a very small difference, but it is essential for the positioning of the satellites that can measure rises in sea level,” he said. “They must be accurate to the millimeter. If the ground stations tracking the satellites are not accurate to the millimeter, then the satellites cannot be accurate either.”

The system of measurement used by the Bonn geodesists (geoscientists who study the size of the Earth) in the two-year project consisted of radio waves that were transmitted into space. “A network of more than 70 radio telescopes worldwide receives these waves. Because the gauging stations are so far apart from each other, the radio signals are received with a slight time lag,” Nothnagel said. “From this difference we can measure the distance between the radio telescopes to the preciseness of two millimeters per 1,000 km.” The procedure is called Very Long Baseline Interferometry or VLBI. The technique can be used, for example, to demonstrate that Europe and North America are moving apart at a rate of about 18 mm a year. The findings were reported in the Journal of Geodesy.

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