This is the smallest thing that can be seen in visible light. A team led by Dave Kielpinski at Griffith University in Australia figured out how to grasp a single ytterbium ion in an electric field, holding it in place so it could be photographed. They shone light on it in a specific frequency, and used an ultra-high-resolution microscope to focus on it. The atom cast a shadow on a CCD detector, which captured the image you see here.