We went to Mercer County Park at about 11:50 for a Memorial weekend retreat. I first noticed Object in the sky after I watched some balloons fly off into the distance and saw a very peculiar one that seemed not to be moving at all. I started watching it for a while seeing if it was going to move or not, and after a couple minutes just thought to myself it was probably just really high up so I'm not noticing the movements down here. After about 10 minutes I decided to look up and see if it was still there, and surprisingly it still was; this is when I called some of the other family members to come look at it to have them voice their opinions on what it could be and after a brief look at it everyone agreed it was a kite that someone just decided to fly really high up (This is when I took a picture to see what it could be). Since that moment about 20-30 minutes went by and looking back I noticed the object still hadn't moved, this is when I noticed a large passenger plane fly by it, showing whatever it was, was a large object. This is when the object then first moved, it appeared slow but compared to the jet's speed it was extremely fast. Roughly 5 minutes afterwards it made an extremely fast jolt towards the right before it rocketed up into the sky until it faded out of view upwards. This is what then made me think it was truly some type of UFO craft.