Sizes and shapes of nuclei with more than 100 protons were so far experimentally inaccessible. Laser spectroscopy is an established technique in measuring fundamental properties of exotic atoms and their nuclei. For the first time, this technique was now extended to precisely measure the optical excitation of atomic levels in the atomic shell of three isotopes of the heavy element nobelium, which contain 102 protons in their nuclei and do not occur naturally. This was reported by an international team of scientists from GSI Helmholtzzentrum für Schwerionenforschung, Johannes Gutenberg University Mainz (JGU), the Helmholtz Institute Mainz (HIM), TU Darmstadt, KU Leuven in Belgium, the University of Liverpool in the UK und TRIUMF in Vancouver, Canada. Nuclei of heavy elements can be produced at minute quantities of a few atoms per second in fusion reactions using powerful particle accelerators. The obtained results are well described by nuclear models, which suggest the nuclei to have a bubble-like structure with lower density in their center than at their surface. The results were published in a recent article in Physical Review Letters.