High altitude point of light makes high speed instantaneous 90 degree turn and accelerates rapidly

I was walking back to my dorm at my prep school on a cold winter evening when I saw a point of light moving fairly rapidly directly from West to East across the clear sky on a track passing somewhat to the North of me.  I had long enough to say to myselt that it seemed to be faster than a satelite, but much slower than a meteor.  When it got directly North of me it made an instantaneous 90 degree turn to the North without changing velocity.  Then it accelerated of over the horizon (New Hampshire) in what seemed like an instant!  I was dumbfounded that an object could seem to make a right angle turn in the air (or space), which seemed to defy the physics I was learning in school.
Date is approximate.  One of two serious-minded reports from same witness.  Please see other report for February 15, 1990, in Boston, MA.  PD