At the time of this sighting I was working at the Mauna Kea Visitor's Station (officially named The Onizuka Center for International Astronomy on Mauna Kea), and setting up telescopes for public viewing. A visitor asked me what the bright light was in the sky, at that point just above one of the local hills, perhaps 20 degrees from the horizon. Since no stars or planets were in that part of the sky at that time, I said "I don't know, lets keep watching it". Just a few seconds after that, the craft made a very subtle "S" turn as it moved towards us. At that point I knew it was something different, so I grabbed one of the 14" telescopes, and as it traveled higher in the sky, I was able to see it two of three tries in the telescope. It looked like an equilateral triangle with a white light on each point. The lights were bright enough to illuminate the edges of the craft which were very strait lines. I hate to use popular media as a reference, but it looked like the craft that is seen in the first episode (or second) of the X-Files.To the naked eye, it was just reflecting sun light and looked like it could have been the ISS in brightness. As it traveled to the NE, it faded from view, I presume entering Earth's shadow around 60-70 degrees above the horizon. Using all that information, and taking the best guess of apparent size in the eye piece that it was 20 meters across. My training is in astronomy so while challenging, that kind of math doesn't scare me.Worth noting that the Visitor center has no street address, I'm not trying to be difficult about that.