High Quality Content by WIKIPEDIA articles! Green fireballs are a type of unidentified flying object which have been sighted in the sky since the late 1940s . Early sightings primarily occurred in the southwestern United States, particularly in New Mexico. They were once of notable concern to the US government because they were often clustered around sensitive research and military installations, such as Los Alamos and Sandia National Laboratory, then Sandia base. Furthermore, the strange green balls of light appeared suddenly and were reported many times per month near such New Mexico installations, but hardly anywhere else.