In this brief note, the implications of a condensed Sun will be examined. A celestial body composed of liquid metallic hydrogen brings great promise to astronomy, relative to understanding thermal emission and solar structure. At the same time, as an incompressible liquid, a condensed Sun calls into question virtually everything which is currently believed with respect to the evolution and nature of the stars. Should the Sun be condensed, then neutron stars and white dwarfs will fail to reach

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... e enormous densities they are currently believed to possess. Much of cosmology also falls into question, as the incompressibility of matter curtails any thought that a primordial atom once existed. Aging stars can no longer collapse and black holes will know no formative mechanism. A condensed Sun also hints that great strides must still be made in understanding the nature of liquids. The Sun has revealed that liquids possess a much greater potential for lattice order than previously believed. In addition, lessons may be gained with regards to the synthesis of liquid metallic hydrogen and the use of condensed matter as the basis for initiating fusion on Earth. "Young people, especially young women, often ask me for advice. Here it is, valeat quantum. Do not undertake a scientific career in quest of fame or money. There are easier and better ways to reach them. Undertake it only if nothing else will satisfy you; for nothing else is probably what you will receive. Your reward will be the widening of the horizon as you climb. And if you achieve that reward you will ask no other." Cecilia Payne-Gaposchkin [1] When Cecilia Payne [1] discovered that the stars are primarily composed of hydrogen [2], she encountered strong opposition from Arthur Eddington, her first mentor, and from Henry Norris Russell [3] . Nonetheless, Cecilia Payne's work engendered a new age in astronomy: hydrogen became the building block of the universe. Russell would eventually come to echo Payne's position [4] . In those days, it was natural to assume that a hydrogen-based Sun would be gaseous [5, 6] . Ten years after Payne published her classic report, Wigner and Huntington proposed that condensed metallic hydrogen could be synthesized [7] . In so doing, they unknowingly provided James Jeans with the material he had lacked in constructing liquid stars [5] . Still, though liquid metallic hydrogen became a component of the giant planets and the white dwarf [8], the concept of condensed matter was kept well removed from the Sun. Now that liquid metallic hydrogen has been advanced as a solar building block (see [8] and citations therein), it is likely that opposition will be raised, for many will foresee unsettling changes in astronomy. A liquid Sun brings into question our understanding of nearly every facet of this science: from stellar structure and evolution [9] , the existence of black holes [10], the premordial atom [11], dark energy [12] , and dark matter [13] . It is not easy to abandon familiar ideas and begin anew. However, some scientists will realize that a liquid metallic hydrogen model of the Sun [8], not only opens new avenues, but it also unifies much of human knowledge into a cohesive and elegant framework. A liquid metallic Sun invites astronomy to revisit the days of Kirchhoff [14] and Stewart [15] , and to recall the powerful lessons learned from studying the thermal emission of materials [16, 17] . It emphasizes that our telescopes observe structural realities and not illusions [18, 19] . In recognizing the full character of these structures, all of the great solar astronomers from Galileo [20], to Secchi [21], to Hale [22] are honored. These observers knew that solar structures (granules, sunspots, pores, flares, prominences, etc. . . ) were manifesting something profound about nature. For astrophysicists, the Sun imparts lessons which may well have direct applications for mankind. For instance, the solar body holds the key to fusion. If the Sun is made from condensed matter [8], then our experiments should focus on this state. Sunspots may also guard the secret to synthesizing metallic hydrogen on Earth [8] . If sunspots are truly metallic [18] , as reflected by their magnetic fields [22] , then attempts to form liquid metallic hydrogen on Earth [8] might benefit from the presence of magnetic fields. Our analysis of the photospheric constitution and the continuous thermal spectrum should be trying to tell us something about liquids and their long range order. It is currently believed that liquids possess only short term order [23] . In this regard, perhaps physics has lacked caution in bombarding the fragile liquid lattice with X-rays and neutrons [24, 25] . These methods may fail to properly sample the underlying structure. Gentler 100 Robitaille P.-M. Lessons from the Sun