Sightings over brasilia sky

The time and hour are not accurate but it happenned in 1975. Me and my family lived in a place vary far from downtown Brasilia. My sister and I were going back home after a school day along with two other grils who lived in the same place. My mother parked the car just in fornt of these two girls' house and we were received by their parents on the porch. I stayed in the front seat of the car. I felt like watching the sky when something started moving. First i thought it was a bug on the windscreen moving sideways. I walked out of the car and could see that there was nothing on the windscreen, then I turned my face up and I could see a small silver circle shaped object making turns very fast, moving sideways and stopping every now and then. I called the people that were just a few meters away from the car and they witnessed the same phe****non. All of a sudden this small object went upwards and a black ring formed around it and it desappeared. This was the first sighting there were another one but this one was really scaring. My sister had to see a psychologist after that. All I can say is that in that place lived the top ranking military generals in the brasilian army and it was well guarded. One of the witnesses was a major in the army. From that day on my life changed. It was like a new understanding of everything. After these two sightings my father invited two military jet pilots for a talk about UFOs. These two pilots confirmed that they had already followed lots of targets over brasilia sky but they were not allowed to speak about it.
Date is approximate.  Witness elects to remain totally anonymous.  PD