I was standing outside on my driveway with a couple of friends and i saw a small circle light drifting?

i noticed that the object was drifting across the sky when i was looking at a star and then the circle light object next to it started moving every so slightly it was very high up higher than the clouds and it kept moving at a constant speed and no noise what so ever but it was also very high we watched it for about a minute it just kept moving constant and then the light started to get fainter and fainter as it was going higher in the sky (circle was the size of about an average star u would see in the sky maybe a little smaller) but the light kept getting fainter and eventually it was gone as it just moved out of the atmosphere and left the earth and the sky was really clear so it did not go up in the clouds and did not have any kind of trail or anything just a slightly moving light can anyone explain this to me as what it might of been because i have no clue