The photograph above is indeed of a single strontium atom, suspended in an ion field and bombarded with lasers. By focusing the high energy light of the lasers on the atom, they excite the electrons, which subsequently will occasionally emit a light of their own. This is coupled with a long exposure shot to make the effect powerful enough to be visible. Could it be seen with the naked eye? Nopes. Was it captured without the aid of a microscope, electron or otherwise? Yes!