Yesterday Google posted a mysterious doodle that linked to the search results for [unexplained phenomenon]. According to Google Korea's blog (English translation), this was the first from a series of 3 doodles that celebrate a famous person. The next doodle will be posted on September 15th and the hints are: mystery, invisible, novel.
As someone suggested in a comment, it's very likely that Google celebrates the birthday of H. G. Wells, a famous science fiction author born on September 21st. He wrote "The War of the Worlds", a novel that describes a Martian invasion, and "The Invisible Man", a book about a scientist that finds a way to become invisible.
Here's an extract from a 1938 radio broadcast of a play based on "The War of the Worlds". The play was directed by Orson Welles and it managed to terrify the listeners, who though it was a news broadcast of a real alien invasion.