A useful explanation may be found here: http://blogs.discovermagazine.com/badastronomy/2012/06/30/wait-just-a-second-no-really-wait-just-a-second/
---rsk
A useful explanation may be found here: http://blogs.discovermagazine.com/badastronomy/2012/06/30/wait-just-a-second-no-really-wait-just-a-second/
---rsk