NASA | Using Quasars to Measure the Earth: A Brief History of VLBI




VLBI, or Very Long Baseline Interferometry, is a technique that uses multiple radio telescopes to very precisely measure the Earth's orientation. It was originally invented back in the 1960s to take better pictures of quasars, but scientists soon found out that if you threw the process in reverse, you could measure how the ground beneath the telescopes moves around, how long days really are, and how the Earth wobbles on its axis as it revolves around the sun! Learn more about VLBI here!

This video is presented in both stereoscopic 3D and standard 2D versions.

This video is public domain and can be downloaded at: http://svs.gsfc.nasa.gov/goto?10964

Like our videos? Subscribe to NASA's Goddard Shorts HD podcast:
http://svs.gsfc.nasa.gov/vis/iTunes/f0004_index.html

Or find NASA Goddard Space Flight Center on Facebook:
http://www.facebook.com/NASA.GSFC

Or find us on Twitter:
http://twitter.com/NASAGoddard More