Large orange illuminated sphere groming in size,stationary, just above treeline next to roadway.

Witnessed a very large Orange sphere hovering just above tree top level as I was driving with my friend on Highway 101 approx. 23:00 hours in June of 1981.  Have wanted to report this every since I witnessed it years ago. It bothers me that I do not know what it was I saw. The Object was in my best estimate 20 to 30 feet in diameter,  And was stationary just above a tree line 30 feet from roadway. It was so bright in illuminated my dash board of my car. We saw it about a 1/4 mile away and thought it was the moon,  As we got closer it was obvious that it was very near to us.We pulled off roadway next to object.  No sound noticeable from object, It was an intense orange color and grew in size as we watched it. It had the appearance of molten glass and as it grew larger what looked like static electricity dissipated from its perimeter.  It grew dimmer as it got larger then simply just vanished only to reappear as a smaller more brighter sphere as before. I felt I co! uld throw a rock at it and hit it as it was so close.  Then it vanishes again. we could see stars in background where object was. Sped home to retrieve a Polaroid camera when we returned we waited at the site, Object never returned. Later on in years I met someone who saw a similar object in the same area!  I am very knowledgeable in physics and am a private sport pilot. But can not identify the object from that night.
Witness indicates that date is approximate.  PD