The Size of Things

    Angular Measure (sexagesimal:babylonian)

       circle is 360 degrees; 60 min/deg; 60"/min

        dia. moon = sun = 1/2 deg = 1800"
        separation of `pointer stars' = 5 deg
        horizon-to-zenith = 90 deg

        fist at arm's length, about 10 deg
        tip of finger                1 deg

        1 arcsecond: a dime viewed ~ 2 miles
                     car headlights viewed from ~ 200 miles
                     1 au from 1 parsec ( = 3.26 ly = 19x10^12)

      
      Time is also 60 s/min and 60 min/hr

      Compared to Earth's circumference:

         360 deg = 40,074 km = 24,400 miles
           1 deg =    111 km =     60 mi
           1 '   =    1.85 km = 1.13 mi = 1 nautical mi
           1 ''  =    31 m    =  101 feet
         0.01''  =    30 cm   =    1 foot  (10 mas)

How big is BIG?

      1000  (in seconds is about 17 minutes)

      10^6  seconds pass in ~ 11 1/2 days

      10^9  seconds pass  in  ~32 years


     1 au = 93 x 10^6 miles
             the concorde (2000mph = 0.55 mi/s) flies that far in
                  46.5 x 10^3 hours = 1,938 days =  5 yrs 4 mos

        so to go 1 parsec would take 1,094,150 years


  The speed of light is

            or    671,000,000    mph

   the moon is       light-seconds away
   the sun  is  ~8.5 light-minutes away