Q:  How many arcseconds does it take to complete a full circle?

          A full circle is 360 degrees, so 

            (360 degrees) * (3600 arcseconds/degree)  =   1,296,000,000 arcseconds


    Q:  How many seconds of time does it take to complete a full circle?

          The sky completes one rotation in 24 hours, so

            (24 hours) * (3600 seconds/hour)          =     86,400 seconds of time




    Q:  How many seconds of time are there in one ordinary day?

            (24 hours) * (60 minutes/hour) * (60 seconds/minute)  =   86,400 seconds of time



    Q:  One second of time is equal to how many arcseconds?


          1,296,000,000  arcseconds around the sky                  arcseconds
         ------------------------------------------------   =  15  -------------
            86,000 seconds of time around the sky                   seconds of time