What i thought was a satellite over Porirua, Wellington, increased in speed and made zigzag and circular patterns.First of all, i am a NZ Customs Officer and a Volunteer Firefighter and take no drugs and had not been drinking at all on the day of this event. I had returned home from my fire station to find my Grandma, her boyfriend, my cousin, his wife, and my uncle watching a satellite fly across the night sky. There were minimal clouds and a full moon. The moon was on the horizon towards the North-East of the sky and the satellite was approximately five vertical fists-lengths above the moon. The satellite was flying North to South at what appeared to be a normal speed compared to other satellites I had seen. All of a sudden the satellite stopped and started flying upwards into the sky, all six of us were amazed and convinced ourselves that it was the international space-station and that it was just changing direction. But then it stopped again, and then rapidly increased its speed, flying in zig-zag and circle patterns. It then appeared to dim and brighten every few seconds, i suspected that it was flying up and down, altering its altitude. I managed to get two photographs taken with my digital camera, in night mode so the shutter was left open for a second or two. and also 8 seconds of video footage with the same camera. The object can be seen moving in a circular pattern in both the time lapse pics, and the video. However a skeptic could explain them as me moving the camera around while filming a bright star. I think not. I went inside to call a friend and when i returned it had disappeared.