We adopt two- and three-body nuclear forces derived at the next-to-next-to-leading-order in the framework of effective chiral perturbation theory to calculate the equation of state of β-stable neutron star matter using the Brueckner–Hartree–Fock many-body approach. We use the recent optimized chiral two-body nuclear interaction at next-to-next-to-leading-order derived by Ekström et al. and two different parametrizations of the three-body next-to-next-to-leading-order interaction: the first one is fixed to reproduce the saturation point of symmetric nuclear matter while the second one is fixed to reproduce the binding energies of light atomic nuclei. We show that in the second case the properties of nuclear matter are not well determined whereas in the first case various empirical nuclear matter properties around the saturation density are well reproduced. We finally calculate various neutron star properties and in particular the mass-radius and mass-central density relations. We find that the adopted interactions based on a fully microscopic framework, are able to provide an equation of state which is consistent with the present data of measured neutron star masses.

In 1918 the only Mexican institution dedicated professionally to astronomical work was the National Astronomical Observatory, which had begun operations in 1878. In that year of the 20th century, Mexico was immersed in the armed movement known as the Mexican Revolution, which strongly affected the social and economic structure of the country. The Mexican astronomers saw their group drastically reduced and their infrastructure limited; however, they made great efforts to continue their participation in the international project of the Carte du Ciel, since they were part of the 18 observatories that originally participated in it. Despite the limitations they suffered, they soon joined the group of seven nations that in 1919 formed the IAU, and two members of that observatory actively participated in the first general assembly held in Rome in May 1922.

The Night-Sky Observation Program (POC, acronym in Portuguese for Programa de Observação do Céu) is the most traditional education activity run by the Museum of Astronomy and Related Sciences (MAST), located in Rio de Janeiro, Brazil. The activity starts with a brief talk about the astronomical objects available for visibility and is followed by the sky observation with MAST’s telescopes, one of them being over a century old. A study conducted in 2015 pointed out that its participants perceive the historical value of the old refractor and declare that the activity brings them feelings of wonderment. These perceptions and declarations have motivated us to conduct a new study to identify and exchange experiences with institutions worldwide that also use historically valuable telescopes in their night-sky observation activities with the public. With the goal of gathering information from these institutions and making it into a guide, an online survey with open and close-ended questions was launched in late 2017. Nearly eighty institutions from all continents answered our questionnaire. The data collected are vast and rich and not only tell about the passion of those mediating such activities, but also the history of astronomy itself.

A brief history of research concerning the risk of impacts by asteroids or comets onto the Earth is presented with attention to the role played by the IAU. Special focus is placed on the events that occurred about 20 years ago, which caused the IAU to become seriously involved in dealing with the impact hazard and to take a leading role in international coordination of these activities.

Can we make a copy of Tycho’s “De Nova Stella” that can in fact survive a nova? At first, this may seem at best a nerdish, if not distinctly foolish question. However, it is also both a technological and a philosophical question: in fact, answering questions like this is linked to both technical, physical and sociological problems related to the long-term preservation and curation of objects from current and past civilizations.

The undertaking presented here is two-fold: Firstly, we report on the results from a state-of the art short-term project, in which we have digitized and analysed three well-known rare books Pertain ing to astronomical observations by Tycho Brahe on the island of Hven. The project led to the creation of free e-books, enabling open access to the sky as recorded by Tycho.

Secondly, we discuss some long-term issues related to the digital and physical preservation of scientific knowledge and heritage in general, exemplified by e.g. the works by Tycho.

Future work includes further physical analysis of the books and fragments, a systematic extraction and digitization of the astronomical observations, digital curation and dissemination, as well as research into the possibility of creating representations and replicas of the works, durable on extremely long time-scales.

At the Sydney IAU General Assembly (GA) the statutes were modified to remove the votes by individual members. Few noticed this at the time but the subsequent reaction by disenfranchised members led us to revise this position in Prague. The need to have a members’ vote on the status of Pluto was complicated by these changes and the drama behind the scene at the Prague GA where the planet definition was resolved is not well known despite the huge public impact of this GA. I will describe some of the activities of the executive and its working groups during this very exciting GA. The IAU structures served us well during this process but of course there were also many lessons learned.

Throughout his career, George Ellery Hale thought globally. “Make no small plans” he was often heard to say (Seares 1939). His early sojourns to Europe, encountering the talent and resources in England and the Continent, contributed to his outlook. He knew that their patronage was critical to reach his personal goals. Here I outline the steps Hale took to establish the new “astrophysics” as a discipline, by creating the Astrophysical Journal, establishing a common language and then, through the first decades of the 20th Century, building an international collaboration to coordinate solar and later all astronomical research. The latter effort, which began in 1904, had expanded by 1910 to encompass stellar astronomy, when the Solar Union deliberated over spectroscopic classification systems, a standard wavelength system and stellar magnitude systems. This work continued through the fifth Union meeting in Bonn in 1913, which turned out to be the last because of the First World War. During the war, Hale became Chair of the National Research Council of the U.S. National Academy of Sciences, applying scientific talent to winning the war. He was also the Academy’s Foreign Secretary, so Hale became deeply involved in re-establishing international scientific relations after the war. In conjunction with Arthur Schuster and Emile Picard, he helped found the International Research Council in 1919, which formed the framework within which the worlds of science reorganized themselves. From this, the International Astronomical Union was born. It was not an easy birth in a world still filled with tension and anger over the war; formative conferences in London and Brussels reflected the extremes. Nevertheless, its first General Assembly was held in Rome in 1922. It would be years before it became truly international, “in the complete sense of the word” (Elis Strömgren), but many of the proposals made during the years of the Solar Union concerning disciplinary standardization were ratified. I will concentrate on this latter story, remembering Hale for his devotion to true internationalism.

A century of existence: it may seem short on the time-scale of the evolution of the universe, but very consequential to that of a scientific association. The fact that the IAU may be able to celebrate such a milestone is in itself a meritorious collective achievement, for it was not obvious at the very beginning that this organization was going to last more than a decade. Drawing on the historical sociology of scientific institutions, my paper will discuss the moral economy through which the IAU – and its dated but persistent form of scientific internationalism – has stabilized and maintained its identity since its creation in 1919, under the unifying auspices of a global scientific object to be known as: Under One Sky.

The IAU is like an old house: Each of the IAU General Secretaries brings her/his individual skills, trying to fix it up. After the collective efforts of several General Secretaries, the house is hopefully kept in reasonable overall shape. But each General Secretary is also in principle responsible for everything, which means that priorities for the way you spend your time must be set – remembering that surprises may occur at any moment.

In my case, I’d like to single out five major initiatives taken during my term, which have probably proved useful in the longer term.