Viewed in summer '90 with mother, colorful orb quietly travel in sky in unconventional manner.

It was the summer of 1990.  I was visiting home from the Univ. of OK for the summer.  My mom had told me stories earlier in the day about how she and a neighbor up the hill had seen a UFO a few times together.  I thought she was "full of it", so she said let's try to see it tonight.  We live in a vally in rural OK.  Not much light, so the sky is highly visible. We looked into the western sky with our naked eyes (where they had previously viewed it).  Only woods and creeks that way.  To my amazement we saw it, shortly after looking for it.  It looked like a bright star at first. But it proceeded to move first slowly, then sharply back and forth and up and down(no particular order).  It changed several colors, but it was so long ago that I can't remember the actual ones.  It was completely quiet.  We should have heard something if it were a conventional craft, because it was pretty close to us.  We didn't report it to authorities, but did tell friends and family.  She(mom) never saw it again after that night.
Date is approximate.  PD