NUCLEAR THERMOMETER. How hot is it inside the nucleus of a dysprosium atom (element 66, abbreviated Dy)? Temperature is a statistical concept that normally applies to an ensemble of many particles, such as air molecules or a gas of atoms kept in a bottle. Inside a heavy nucleus, swarming with protons and neutrons (collectively called nucleons) it's not so easy to define temperature, owing to the many pairing and other inter-nucleon interactions that take place, but it can be done. The nuclear environment can be sampled by colliding nuclei together and then carefully measuring the photons that fly out: high energy gamma rays, in this case, rather than the visible and infrared photons that come out of heated-up atomic gases. In this way, physicists at the University of Oslo have deduced the temperature inside a Dy nucleus (in effect, a gas of 162 nucleons) to be 6 billion K. It can be said, therefore, that even in winter parts of Norway (very small parts) remain quite warm. This is the first time a nuclear temperature has been measured strictly on the basis of the spectrum of gammas emitted. (E. Melby et al., Physical Review Letters, 6 September 1999; contact Magne Guttormsen, magne.guttormsen@fys.uio.no, 011-47-2285-6460.)