My family and i were sitting in our house one night around 8:30 pm, after dark, and heard what we thought was a very low flying helicopter, that came approaching fast. my daughter and i ran to the front of the home where we both thought it was coming from, then we realized it was already over our home, so we ran out the back. it looked as if it was stoped then began to move quickly away. we could only catch sight of the back of it, as it quickly flew over the tree line. the only way i could describe it to my husband was it looked like an airboat shaped bottom, with two glowing large green fans or engines on the back, it looked like an airboat. i just couldn't believe it was flying. green round giant engines, like circles. only two at the back of it. i called the air force base and reported it, they claimed they had nothing flying around us, and i told them it was extremely close to our house. they claimed there was nothing. four of us heard the sound but my daughter and i both saw it.