I am a amateur astronomer living about 45 miles north of houston. i'm 25 miles north of iah. i have seen aircraft of every description and many different kinds of running lights...This was very different from anything i have seen before. the sky was cloudless and had good visibility. i noticed the object about 11:20pm and thought it might be a high flying jet. it appeared to be moving too slowly to be a jet and for the same reason i concluded that it was not a satellite. using a pair of 11x80 binoculars i could not detect any body to the craft indicating low reflectance, great distance or small size. at less than 10,000ft i generally can see some detail on jets at night with the 11x80 binoculars as they have about a 6mm exit pupil. my guess is that the craft was between 15k and 35k feet in altitude and moving between 100 to 200 mph. i think the most unusual aspect was the oscillating light. it was beacon like and white. no other light colors were ever observed. if you can imagine a lighthouse on its side, five or six miles up with the light rotating every 20-40 seconds. the light appeared to be rotating on an axis that was parallel to the ground. it was not a strobe light, this light appeared to shine directly into my binoculars as it rotated in my direction and then away. to the naked eye this beacon effect was not visible, only a change in brightness from invisible to visible and then bright(as the light scanned past me). one other observation...I live out in the country...Its quiet. there was no sound detected. regards, stan simpson