The second map plots the reports week by week—just click on an icon to read a description of the sighting. In many cases, several people report what appears to be the same incident. For example, there was a huge cluster of UFO spottings in the Northeast on Sept. 19, 2009. (NASA launched a rocket experiment in Virginia that night.) Astronomical events are often misidentified as well, such as in the third week of November 1999, when several people reported seeing a UFO in the Midwest. It was the same night as the Leonid meteor shower. Reports also spike in the first week of July.