Celebrating 50 Years of Satellite Laser Ranging at NASA Goddard Space Flight CenterRelease Date: 08/28/2014 We like to think of Earth as a big blue marble; a shimmering, smooth sphere. In reality, our home planet is shaped more like a big blue potato (or, to be polite and more scientific, an "oblate spheroid"). The combination of Earth’s rotation at roughly 1,670 kilometers per hour, the uneven distribution of continents that are slowly moving, the Moon’s tug on tides, ocean circulation, and a host of other factors cause our planet to have an uneven surface that is a bit flat at the poles and slightly bulging around the middle.

This means that the Earth’s exact shape, center of gravity, and precise rotation are constantly changing and can only be determined through extremely precise measurements. An entire field of science called geodesy is devoted to taking these precise measurements, and Goddard Space Flight Center is at the leading edge of this field. In fact, it was in a field near Goddard 50 years ago this October that the first successful Satellite Laser Range (SLR) measurements were taken, ushering in a new era in the science of measuring the Earth.

Read more