Light observed above Jefferson County, Colorado moves from over-head stationary position to beyond the East horizon in seconds.

I am a dual-degree engineer from the Colorado School of Mines.  This occurred when I was 12 but at the time (May, 1989), I understood that what I saw wasn’t possible with current technology.  Two friends and I had snuck out during a sleep over and were at a park, just after midnight, in central Jefferson County, Colorado.  We noticed a Stationary bright light  at about 15-20 degrees south of vertical.  At the time it appeared to me as an aircraft coming toward us - as it had no lateral movement but was much brighter than anything in the sky. It kept this position for several minutes.  As we began to walk back toward the house we were staying at we felt like it was moving with us (with my current knowledge, that can be explained as parallax).  Then, from a stationary position, the light moved at a high rate of speed to the East and disappeared over the horizon in a few seconds without leaving any sort of trail.  The horizon line from our vantage point was maybe 50 mi! les and depending on the “craft’s” altitude, could mean several hundred miles of travel for it pass beyond.  There was little or no acceleration period to get to speed - it went from stationary to really fast almost immediately.  Although young, I understood that what I saw wasn’t possible. I remember it vividly.  Just never thought about reporting it until now. I truly hope it coincides with other data the UFO Center may have.  It’s stuck with me throughout my life and, as an engineer, remains the only unexplainable thing I’ve witnessed.