A craft with a portal

NOV. 28, 2009  I have been wanting to tell someone about my sighting for a long time, not because I saw a UFO but because of pieces of information that may have some significant value.
This was in the late 60's in California.  I was maybe 15 at the time, living with my parents. I was sleeping, in my own room at the rear of the house, when I was awakened by a noise.  It was the sound that a jet would make, however it was of a slightly different pitch, I knelt on my bed looking out of my window and was frozen in place by the sight of a UFO hoovering approx. 100' above our neighbors and our house.  This UFO was the stereotypical UFO for the time and I am not sure that I could even describe it accurately now.  This craft hoovered maybe 15 seconds in this spot ( which seemed like 15 minutes ) and then it departed in a vertical direction until it was pretty high, before moving horizontally.  The next thing that happened was pretty cool.  It was a clear night with a lot of stars visible and I was watching this craft depart out of frozen, excited, curiosity.  It was traveling horizontally when it came to a spot in the sky that was pure black, no stars, and darker in! color than the night sky, as it got to this spot it turned into it an vanished instantly.
I was disappointed that it was gone because I wanted to continue to watch and follow this craft, but I was excited because I felt I knew a little something that others didn’t, and that was an explanation of how they are able to travel such great distances.  I have told very few people of this sighting because they tend to not believe you, and I have never really known who I could give this information to. If this information helps in any way than my job is done.  Thanks.
Witness indicates that date is approximate.  PD