At temperatures as hot as the sun and under pressures over a million times atmospheric pressure, the metal molybdenum melts. Tracking the molten history of the metal clarified the melting point, the border between solid and liquid phases. To track the melting process, a team focused an x-ray beam into the tight confines between two ultra-hard diamond micro-anvils. A laser heated the small volume. The x-ray beam allowed the tracking of fine features that uniquely formed from the melted metal and were a clear indication that melting had occurred.