Since more than a decade it has been possible for physicists to accurately measure the location of individual atoms to a precision of smaller than one thousandth of a millimeter using a special type of microscope. However, this method has so far only provided the x and y coordinates. Information on the vertical position of the atom -- i.e., the distance between the atom and the microscope objective -- is lacking. A new method has now been developed that can determine all three spatial coordinates of an atom with one single image.