Crop circles are spotted in an unexpected place today: the Google homepage. So, what is this all about?

Google often swaps its logo for big events like holidays or anniversaries. However, today's picture seems to be different. Google visitors are greeted by an alien-themed logo.

The site is showing a logo consisting of crop circles with a UFO and a tractor finishing of one of the letters.

To add to the mystery, Google tweeted these map coordinates Tuesday morning. Several websites report they pinpoint to the center of a small town called Horsell in England.

If you're familiar with H.G. Wells' War of the Worlds – you might know that that's the town where the first UFO landing was witnessed in the novel.

Google ran an alien-themed logo last week as well.

So why this change of logos? Some Tweeters think they've got it figured out.

Well's birthday is just six days away. That's why some Tweeters believe the images are references to the upcoming milestone.

But no one is really sure. So, with people eager for more answers, online searches for google crop circles hit volcanic popularity this morning.

While you're waiting for answers, check out some crop circles pictures and videos!