Google's "Unexplained Phenomenon" Logo

Google's latest logo today features an image of a UFO with a link to the search term "unexplained phenomenon". I searched around the web but no one was sure what the story is behind this logo. I thought maybe this photo is proper for today. However, an "unexplained phenomenon" is not always in or from the space. There are many unexplained phenomenons on the earth or even in our social life. Well, maybe this photo is more suitable for July 20, the moon landing annivesary. Anyway, I hope you like it.