Basically its about an event that occurs in modern day Los Angeles which results in meteors striking Earths surface and an attacking alien race invading Earth and extermenating humans for Earths resources. Its a pretty crazy movie and the trailer is beyond spooky.

Enjoy it. Also I would chaulk this down as one of the greatest movie trailers of our time.

http://www.youtube.com/watch?v=SEOQAEbpnvc

Also apparently an event occured in the early 1900's that resulted in people seeing and hearing an airspace battle only to be shut down by a Military Officer claiming it was flares and disfigured weather baloons.