Bright white "hole" in deep blue noon sky on steady path. No structure apparent.

During a clear noon with no clouds and dense blue sky, I looked straight up (12 o’clock) and observed something slowly moving across the sky at apparently extreme altitude.
	I stared at it for a good 15 min with my school mates.
	No structure could be seen. No lights.
No color, just an extremely bright solid white dot crossing the sky with a brightness rivaling the sun, but NO glare.
	This white dot appeared to be not much smaller than a dime at arms length.
	To me it looked just like “a White Hole in the blue sky.”  My best description!  
	Incidently, there was also a Nike missle base not far from this location.