The Greenwich Prime Meridian is one of the iconic features of the Royal Museums Greenwich. Visitors to the Museum even queue up to pose with one leg on either side of the Line. Yet, the Airy Transit Circle, the instrument that defined the meridian, is almost always excluded from these photographs. This paper examines how the instrument has become hidden in plain sight within the stories of Greenwich Time and Greenwich Meridian, as well as within the public imagination, by providing an analysis of the instrument’s transformation from a working astronomical instrument to a museum object. The paper highlights the gradual decoupling of the instrument from narratives of Time and Longitude, which resulted in the Line’s popularity overshadowing the instrument that defined it. By doing so, the paper aims at showing the symbiotic relationship between the materiality of the instrument and the meridian line that it defined. Approaching the instrument through the lenses of object biographies, the paper raises the question of whether the life of the instrument came to an end once operations with it were terminated. The analysis of the Transit Circle’s life reveals that it reached its end multiple times, which shifts the emphasis away from a single and ultimate end of scientific objects to a process of gradual downfall, during which they can “end” several times. In addition, through the object biography approach, the Transit Circle no longer appears as a dead object reaching an afterlife within a museum setting. Instead, the approach demonstrates that, though the instrument can still be restored to an operational order, doubts about its accuracy, and its relevancy to today’s astronomical methods, have led the instrument to be considered obsolete, transforming it into a museum object on display.

In the context of the European Middle Ages as the period roughly covering from the 5th to the 15th centuries, the astronomical records are rarery found in scientific treatises. At least, not until the 15th century. A few surprinsing examples in which the observations were recorded in a particularly original way on stone are found. In this poster we will shortly review the only four cases in which this occurred in Europe.

Galaxy Forum (GF) South America 2020, was held virtually on December 8, 2020 on the opening eve of IAU 367 by the International Lunar Observatory Association (ILOA Hawai’i) with the support of the Instituto de Tecnologías en Detección y Astropartículas (ITeDA, CNEA-CONICET-UNSAM) and IAU. Galaxy Forum is an education and outreach program sponsored by ILOA, an interglobal enterprise incorporated in Hawaii as a non-profit organization to expand human knowledge of the Cosmos through observation from our Moon and to participate in internationally cooperative lunar base build-out.

As a IAU-367 associated event, Galaxy Forum featured comments by Dr. Beatriz Garcia and presentations by ILOA Director Steve Durst (ILOA Hawai’i, USA), Marcelo Colazo (CONAE, Argentina); César Gonzalez García (CSIC, Spain); Li Geng (NAOC, China); Santiago Paolantonio (Córdoba Observatory, Argentina) and Margarita Safonova (IIA, India). In this contribution, the overview of the contributions permits an approach to the GF interests.

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.

The aim of this work is to provide new information about the history of astronomical science and the efforts of the people that have enriched our discipline, often coming from anonymity. Here we compile the attempts made in our country to prove the theory of General Relativity through experiments that, as they were without success, fell into oblivion.

The IAU was founded in 1919 “to facilitate the relations between astronomers of different countries where international co-operation is necessary or useful” and “to promote the study of astronomy in all its departments”. These aims have led the IAU throughout the century of its existence, but the way it has tried to fulfil them has changed. We have tried to trace the changing role of the IAU in the international astronomical community through the twentieth century and into the twenty-first. The IAU has striven – occasionally struggled – to protect international scientific cooperation across the deep political divides that characterized the 20th century, while maintaining an important function in the context of the rapidly evolving science itself and the changing fabric of institutions involved in astronomy. We especially argue how the emphasis of the IAU’s activities has shifted from the first aim – facilitating collaboration by organizing meetings and defining common standards – to the second aim: promoting astronomy by outreach and development programs.

2017 marked the 130th anniversary of the start of the Carte du Ciel project, an ambitious proposal by the Paris Observatory to map the entire sky using photographiy, which required the joint work of numerous observatories in the world. For this endeavour, an impressive organization was designed that included congresses, commissions and publications, which lasted through many years. The Carte du Ciel finally became one of the immediate antecedents of the International Astronomical Union, which in 2019 celebrates its first century. In Latin America, the observatories of Santiago de Chile, La Plata and Rio de Janeiro, the Argentine National Observatory and the Tacubaya Observatory, in Mexico, were involved in the project. In this presentation, we present part of the history of the failures and successes of one of the most important collaborative astronomical projects on the planet.

Astronomy in Japan has long history and has its own “light”. The foresight of leaders in the early 20th century helped Japan to become a founding member of the International Astronomical Union. In this paper, a brief description will show the growth in its more recent history with particular emphasis on two important issues: large research facilities and women participation. On the ground or above, the large observational facilities are nowadays outside of the land of Japan, not only in terms of physical presence but also the community they serve. Domestic membership of the Astronomical Society of Japan at the same time is expanding, thanks to the increased opportunities for women. Continuing global cooperation with more diverse composition of members are the keys for sustaining the growth to carry the astronomy in Japan with IAU into the next century, and hopefully to another planet.

The astronomical community accepts the division of the celestial sphere into 88 constellations, according to what was established by the IAU. In the first Assembly of 1922 the use of Latin names for constellations and their abbreviations was resolved. The pending issue of the limits of the constellations was discussed in the next meeting and Eugène Delporte had the responsibility for the complete theoretical demarcation. For his work, Delporte took into account what was done half a century earlier in the famous work Uranometría Argentina, published in 1877 and 1879, under the supervition of Benjamin Gould. In ths presentation we discusse the situation at the moment when the constellation boundaries were proposed using arcs of RA circles and parallels of declination, choosing them in such a way that they did not deviate too much from those used in the most important celestial atlas of the time, and minimizing the changes of which constellations stars would belong to.

The first hundred years of the IAU have witnessed scientific and technological progress in astronomy beyond anything imagined at the time the IAU was founded in 1919. What will the next hundred years bring? How do we engage with other sciences, now that our field is becoming more multidisciplinary? How do we convince governments to continue funding our field, in particular the ever more powerful telescopes? And how do we continue to inspire and involve people worldwide in our exciting adventure through space? A brief forward look into the next decade and beyond is presented, with some challenges highlighted.

Astronomy, astrophysics and cosmology have changed out of all recognition over the last 100 years. The IAU has provided an essential means of fostering international collaboration in these disciplines including times of international tension. Developments will be highlighted which have profoundly changed our understanding and insight into the workings of our Universe.

Due to its unique 400-year duration, the sunspot number is a central reference for understanding the long-term evolution of solar activity and its influence on the Earth environment and climate. Here, we outline current data recovery work. For the sunspot number, we find historical evidence of a disruption in the source observers occurring in 1947–48. For the sunpot group number, recent data confirm the clear southern predominance of sunspots during the Maunder Minimum, while the umbra-penumbra ratio is similar to other epochs. For the Dalton minimum, newly recovered historical observations confirm a higher activity level than in a true Grand Minimum.

We give an overview of Focus Meeting 5 on the new field of Terra-Astronomy.

Stone inscriptions from all over India provide records of eclipses, solstices and planetary conjunctions. Extending the study to South Asia, to include Cambodia, Sri Lanka, Nepal and Thailand, threw light on many new aspects such as evolution of calendars independently from the influence of Indian system of time measurement as early as the 3rd Century BCE. Many interesting records of planetary conjunctions are available. One record from Cambodia hints at a possible sighting of the 1054 supernova, while another from Thailand suggests a pre-planetary nebula event.

A Danish computer, GIER, from 1961 played a vital role in the development of a new method for astrometric measurement. This method, photon counting astrometry, ultimately led to two satellites with a significant role in the modern revolution of astronomy. A GIER was installed at the Hamburg Observatory in 1964 where it was used to implement the entirely new method for the measurement of stellar positions by means of a meridian circle, at that time the fundamental instrument of astrometry. An expedition to Perth in Western Australia with the instrument and the computer was a success. This method was also implemented in space in the first ever astrometric satellite Hipparcos launched by ESA in 1989. The Hipparcos results published in 1997 revolutionized astrometry with an impact in all branches of astronomy from the solar system and stellar structure to cosmic distances and the dynamics of the Milky Way. In turn, the results paved the way for a successor, the one million times more powerful Gaia astrometry satellite launched by ESA in 2013. Preparations for a Gaia successor in twenty years are making progress.

This paper aims at contributing to the UNESCO-IAU Astronomy and World Heritage Initiative's discussions by presenting the case study of a 20th-century observatory located in a South American country. In fact, the National Observatory of Brazil was created in the beginning of the 19th century, but its present facilities were inaugurated in 1921. Through this paper a brief description of the heritage associated with the Brazilian observatory is given, focused on its main historical instruments and the scientific and social roles it performed along its history. By way of conclusion, the paper suggests that the creation of the Museum of Astronomy and Related Sciences with its multidisciplinary team of academic specialists and technicians was decisive for the preservation of that expressive astronomical heritage.

Australasian amateur astronomers, Grigg and Ross, discovered four different comets between 1902 and 1907. Controversy surrounding these discoveries led to a deterioration in relations between Australia's leading amateur astronomers and Baracchi at Melbourne Observatory, and to the eventual transfer of the ‘Australian Central Bureau’ to Sydney Observatory.

Robert Innes was one of a select band of amateur astronomers who made the transition to professional ranks towards the end of the nineteenth century. Initially he had a passion for mathematical astronomy, but after settling in Sydney he developed a taste for observational astronomy, specialising in the search for new double stars. He quickly became known for his success in this field and for his publications on solar system perturbations, and with John Tebbutt's patronage managed to secure a clerical position at the Royal Observatory, Cape of Good Hope. Once there he continued to observe in his spare time and to publish, and, with strong support from Sir David Gill, was appointed founding Director of the Transvaal Observatory. By the time he died in 1933, Innes had received an honorary D.Sc. from Leiden University, and had established an international reputation as a positional astronomer.This paper provides an interesting case study of a well-known ‘amateur-turned-professional’, and an example of the ways in which patronage played a key role in nineteenth and early twentieth century Australian and South African astronomy.

The purpose of this invited commentary is to present some general closing remarks on the global content of the ‘Oxford IX’ International Symposium on Archaeoastronomy, taking into account how we evaluate the course archaeoastronomy has taken over the past few years. It is significant that the interdisciplinary field of archaeoastronomy has already, by common consent, changed its name into ‘astronomy in culture’ (or ‘cultural astronomy’). This happened several years ago, although it is still the case that the cultural aspect (cosmovision, or vision of the world) is not always taken sufficiently into account. The keynote presentations by Ruggles, Iwaniszewski and McCluskey addressed fundamental issues of method and theoretical concepts that should guide archaeoastronomical studies. The rest of the sessions as well as the posters were dedicated to case studies from different cultural regions of the world. This commentary synthesizes several common themes that were addressed in the many interesting papers from all over the world that were presented in the meeting. Finally I take up the proposition of Gary Urton that future efforts should be concentrated on the study of the production and maintenance of systems of knowledge in complex state societies as well as in more egalitarian rural communities. In my opinion it is an urgent task to begin discourse about the history of pre-Columbian civilizations in the Americas, a discipline of which the history of science and astronomy forms a fundamental part. The ‘Oxford’ International Conferences are a key forum for exchange and encounter regarding comparative studies with other ancient civilizations as well as indigenous traditions from all over the world.

Galileo's stunning discovery of the four largest satellites of Jupiter forced the over throw of the Earth-centered cosmology that had dominated astronomy for centuries. Such a fundamental transformation of the Western World's view of its importance in the cosmos could be expected to produce some humility in society. However, the deep desire for our uniqueness continues to struggle with the astronomical evidence.