This is an optical illusion in which a static image appears to be moving due to the cognitive effects of interacting color contrasts and shape position. Image File:Motion illusion in star arrangement.png by Fiestoforo and licensed under the Creative Commons Attribution 3.0 Unported license. on the Wikimedia Commons.
Many but not all of the images on this blog are under a Creative Commons License. If and only if the image above is under a Creative Commons license, you can find details for the different licenses at the Creative Commons. The most common licenses are Attribution CC-BY 2.0; 2.5; 3.0; and 4.0; and Attribution Share Alike CC-BY-SA 2.0; 2.5; 3.0; and 4.0;