I’ve been getting emails about these “structures” on the moon.
As you can see, the image is courtesy of NASA and Google Earth software. It comes from the second link noted below.
Sorry, folks, these are not artificial structures. There is no alien moon base.
This discussion from the Discover Magazine blog goes through what they are and why, with lots of illustrations. They digital imaging artifacts (i.e., the objects are created are residual effects from the camera, light, imaging process, etc.).
As good as that link is, this one is even better (it’s referenced within the first one). It takes you step-by-step as to how these images happened. It even has motion gifs illustrating how the are recreated and manipulated. Really cool stuff.