spheroid, leading edge shimmering red, main body whitish yellow, low altitude

About the same time what had caused me to look up in the sky was a loud roar of a jet - clearly military by the sound of it.  The jet was going east to west and this sphere was low going west to east.  It didn't look like any weather balloon, no odd shapes dangling, or geometry.  
It wasn't at all high up.  Hard to tell size, but I would say about 20 feet in diameter. It wasn't translucent, didn't change shape, or seem to bounce at all, but had a definite direction heading towards Lakewood, CO.  
As it reached the front range, it looked like it turned back to the west, and I watched it slowly getting larger again until it was blocked by trees.  
This is the second time I have seen something like this in the same approximate location and duration. - The previous event was in 2004.