Typicality arguments attempt to use the Copernican Principle to draw conclusions about the cosmos and presently unknown conscious beings within it, including extraterrestrial intelligences (ETI). The most notorious is the Doomsday Argument, which purports to constrain humanity's future from its current lifespan alone. These arguments rest on a likelihood calculation that penalizes models in proportion to the number of distinguishable observers. I argue that such reasoning leads to solipsism, the belief that one is the only being in the world, and is therefore unacceptable. Using variants of the ‘Sleeping Beauty’ thought experiment as a guide, I present a framework for evaluating observations in a large cosmos: Weighted Fine Graining (WFG). WFG requires the construction of specific models of physical outcomes and observations. Valid typicality arguments then emerge from the combinatorial properties of third-person physical microhypotheses. Indexical (observer-relative) facts do not directly constrain physical theories, but instead weight different provisional evaluations of credence. As indexical knowledge changes, the weights shift. I show that the self-applied Doomsday Argument fails in WFG, even though it can work for an external observer. I argue that the Copernican Principle does not let us apply self-observations to constrain ETIs.

At the 1988 IAU General Assembly in Baltimore, among many who offered reminiscences of earlier meetings was Charlotte Moore Sitterly. She first attended the 1932 GA meeting, in Cambridge, Mass., though she already “helped to assemble material for delegates” since the 1920s, for astronomers at Princeton, Mount Wilson and Lick Observatory. She was an ardent member of the new Commission 14 (then called “Fundamental Spectroscopic Data”), eventually becoming its president. In her 1988 reminiscence, she recalled that the Commission meeting was sparsely attended and very informal, but astronomers’ “never-ending demand for tables and data analysis” soon changed all that (Sitterly 1988). Here we provide a brief overview of how Charlotte Moore Sitterly came to be at the very center of that change, which Donald Menzel early on described as having “turned chaos into order” and just a “little short of miraculous” (Menzel 1928) We will recount highlights of her early life, aspirations, training, and contributions during her years at Princeton, Berkeley, Mount Wilson, and the National Bureau of Standards.

The communication project “Herschel and the invisible end of the rainbow” features the year 1800 discovery and today’s application of infrared radiation through diverse methods and different media in order to reach a wide audience. The discovery of the sun’s infrared radiation by the Herschels is demonstrated in a creative way through the publication and performance of a theatre play and accompanying audio play. The documentation of the historical discovery, which changed both science and our daily life, is further supplemented by background information e.g. on the role of women in science in the late 18th and early 19th century. By this, the history of the discovery of infrared radiation becomes alive and easily comprehensible. Additionally, we carry out interactive experiments and demonstrations using a capable thermal infrared camera by which a mostly unknown and strange infrared world becomes visible for all generations. Our recent findings with the infrared space telescope Herschel are used to exemplify modern science use. With this colourful, diverse and interactive communication concept, which is easily extendable and adaptable, we already took part in several science festivals, workshops and training events.

The impressive transition from an era of scientific data scarcity to an era of overproduction has become particularly noticeable in archaeoastronomy. The collection of astronomical information about prehistoric societies allows the accumulation of global data on: – the oldest traces of astronomical activity on Earth, emotional and rational display of celestial phenomena in astronomical folklore, “folk astronomy” and timekeeping, in fine arts and architecture, in everyday life; – the most ancient applied “astronomy” – counting the time by lunar phases, accumulation and storage of ancient databases in drawings and pictographic compositions in caves and artificially constructed objects; – “horizon” astronomy as an initial form of observational cult astronomy, preserved only in characteristic material monuments (the oldest cult observatories) with indisputable astronomical orientations. The report shows the importance of collecting the maximum number of artifacts and monuments from prehistory associated with the early emergence of interest in celestial phenomena. Spiritual, emotional and rational (including practical) needs that have aroused interest in Heaven are discussed. The huge variety of activities in realizing the regularity (cyclicity) of celestial phenomena as a stimulus for their use for orientation in space and time is shown.

This contribution summarizes the reconstruction of historical constellations. It is based on studies of classics, philologies, history of science and history of art. In the given brevity, I can only sketch the strategic, scientific and educational reasons.

Girls’ under-representation in science, technology, engineering and mathematics (STEM) education is deep rooted and puts a detrimental brake on progress towards sustainable development. Both education and gender equality are an integral part of the 2030 Agenda for Sustainable Development, adopted by the United Nations General Assembly in 2015, as distinct Sustainable Development Goals (SDGs). The UNESCO Report: Cracking the code: Girls’ and women’s education in STEM provides a global snapshot of this underrepresentation and the factors behind it. The fight against stereotypes to ‘crack the code’, or to decipher the factors that hinder or facilitate girls’ and women’s participation in STEM (and particularly in Astronomy) education must take into account the persisting dichotomy between the so called two cultures.

The US astronomy/astrophysics community comes together to create a decadal report that summarizes grant funding priorities, observatory & instrumental priorities as well as community accomplishments and community goals such as increasing the number of women and the number of people from underrepresented groups. In the 2010 US National Academies Decadal Survey of Astronomy (NRC10), it was suggested that having to move so frequently which is a career necessity may be unattractive to people wanting to start a family, especially impacting women. Whether in Europe or elsewhere, as postdocs, astrophysicists will relocate every two to three years, until they secure a permanent position or leave research altogether. Astrophysicists do perceive working abroad as important and positive for their careers (Parenti02); however, it was found that the men at equal rank had not had to spend as much time abroad to further their careers (Fohl12). By implication, women need to work abroad longer or have more positions abroad to achieve the same rank as men. Astrophysicists living in the United Kingdom prefer to work in their country of origin, but many did not do so because of worse working conditions or difficultly finding a job for their spouse (Fohl14). In sum, mobility and moving is necessary for a career in astrophysics, and even more necessary for women, but astrophysicists prefer not to move as frequently as needed to maintain a research career. To gather more data on these issues and to broaden the discourse beyond male/female to include the gender diverse as well as to include other forms of diversity, the ASTROMOVES project was created which is funded through a Marie Curie Individual Fellowship. Though slowed down by COVID-19, several interviews have been conducted and some preliminary results will be presented.

The development of astronomy has been developed by the cooperation of amateur astronomers and researchers. Sunspot observation is a good example of Extreme citizen science in early days. Issei YAMAMOTO (1889–1959), organized “Oriental Astronomical Association (OAA),” Yamamoto’s materials (now in Kwasan observatory) include solar observation data sent from many observers in Japan. From the viewpoint of today’s Citizen Science, collaborative observation of sunspot between researchers of solar physics and amateur astronomers in Japan has clearly a context of social mission rather than mere academic interest. From the viewpoint of science communication, we can see that Yamamoto’s call includes a social mission to promote astronomy in Japan, and that amateurs responded to Yamamoto’s call by participating in the observation network. It can be said that this collaboration have not only “cultural” aspect but also “civic”or “practical” aspect.

The report shows the current opportunities for obtaining astronomical knowledge in school and outside it, through the use of non-formal education. These are school and extracurricular activities, schools, astronomical competitions and Olympiads, observation expeditions. For 25 years Bulgaria has been participating in the International Olympiads in Astronomy and Astronomy and Astrophysics with National Teams. The role and place of the system of Public Astronomical Observatories and Planetaria in the system of non-formal education in astronomy are discussed (In Bulgaria there are 7 Public astronomical observatories with a planetarium). Specialized activities in their school forms allow the formation of sustainable astronomical knowledge and observational habits.

How special (or not) is the epoch we are living in? What is the appropriate reference class for embedding the observations made at the present time? How probable – or else – is anything we observe in the fulness of time? Contemporary cosmology and astrobiology bring those seemingly old-fashioned philosophical issues back into focus. There are several examples of contemporary research which use the assumption of typicality in time (or temporal Copernicanism) explicitly or implicitly, while not truly elaborating upon the meaning of this assumption. The present paper brings attention to the underlying and often uncritically accepted assumptions in these cases. It also aims to defend a more radical position that typicality in time is not – and cannot ever be – well-defined, in contrast to the typicality in space, and the typicality in various specific parameter spaces. This, of course, does not mean that we are atypical in time; instead, the notion of typicality in time is necessarily somewhat vague and restricted. In principle, it could be strengthened by further defining the relevant context, e.g. by referring to typicality within the Solar lifetime, or some similar restricting clause.

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.

The International Astronomical Union was conceived in 1918, and was formed one year later in Brussels. One of the 32 initial Commissions was the Committee on Stellar Photometry that later on became IAU Commission 25 Astronomical Photometry and Polarimetry, and since 2015 Commission B6 with the same name. The initial functions to be exercised by the Committee were

1. (a) to advise in the matter of notation, nomenclature, definitions, conventions, etc., and

2. (b) to plan and execute investigations requiring the cooperation of several observers or institutions.

The basic philosophy was that IAU Commission 25 was to be an advisory body, rather than a decision-making committee that imposes its regulations. This position was reconfirmed at the 10th IAU General Assembly in 1958.

From the early days on, the Commission members engaged in the teaching of the principles of photometric measurement – either via the Commission meetings and the ensuing reports, or via external means, such as lectures and publications. The topics of instruction dealt with absorption of light in the atmosphere, the modification imposed by the character of the receiving apparatus, the unequal response of different receivers to a same stimulus, and variations in the data-recorder response from one experiment to another.

From the 1930s on it was suggested that IAU Commission 25 takes responsibility in matters of standard stars, standard filters and standard calibration methods.

During the first half-century since its foundation, Commission 25 was an active forum for discussions on the basic principles of astronomical photometry, including the associated problems of transformability of magnitudes and colour indices from one instrumental configuration to another. During the second half-century of its existence, the Commission has served as a sort of news agency reporting on the developments in detector engineering, filter technology and data reduction. All along the Commission members were committed to accuracy and precision, a struggle that was primarily driven by the jumps forward in performance and sensitivity of every new detector that was introduced.

The development over one century shows that the Commission was continuously touching on the philosophy of precise measurement, where accurate measuring – for a select group of pioneers – was an end in itself.

This presentation looks back on the opinions of key players in the photometric standardisation debate, and briefly presents two case studies that illustrate the illusionary accuracy reached over a century in determining, as Commission member Ralph Allan Sampson put it, “a detail like magnitude”.

This year 2018 has great historical and current significance for stellar spectral classification. Two hundred years ago in Reggio Emilia, Italy, was born Angelo Secchi, a pioneer of observing and classifying the spectra of stars. At the beginning of the IAU, almost a hundred years ago, one of its original Commissions was entitled the Spectral Classification of Stars, from which was generated Commission 45, Spectral Classification and Multi-band Colour Indices. And seventy-five years ago, was published the system-changing MKK, An Atlas of Stellar Spectra. Through this necessarily brief, historical view we shall recall how spectral classification, supported internationally by the IAU, continually updated its techniques, while remaining anchored to standards. This has ensured that the MK classification process stays very relevant to the initial characterizing of stars in the 21st century era of large spectral surveys.

We briefly discuss the history of membership and the current position of Serbia inside the International Astronomical Union. We give an overview of astronomy education, research and public outreach in Serbia. Some statistics are presented concerning the number and gender of BSc, MSc and PhD students that graduated/obtained their degree in astronomy/astrophysics from the Department of Astronomy, Faculty of Mathematics, University of Belgrade. Due attention is paid to the most important scientific/educational institutions in Serbia in which the majority of astronomers are employed as well as various research topics investigated.

Sources from Ancient Mesopotamia contain mention of transient astronomical phenomena in two contexts: in records of observations, many of which can be dated, and in collections of omens, which use the appearance of such phenomena to predict future events. These omens consider quite a range of phenomena, but only rarely can they be dated in a precise way. This paper describes how transient phenomena were handled in both kinds of context.

This paper discussed whether 17th Century observers left historical records of the plasma tails of comets that would be adequate to enable us to extract the physical parameters of the solar wind. The size of the aberration angle between a comet’s tail and its radius-vector defines the type of the tail: plasma or dust. We considered Bredikhin’s calculations of the parameters for 10 comet tails observed during the Maunder minimum (1645 – 1715). For those comets the angle between the tail’s axis and the radius-vector on average exceeded the value of 10° that is typical for dust tails. It was noted that visual observations of the ion tails of comets are very difficult to make owing to the spectral composition of their radiation, confirming the conclusion that observations of comet tails made in the 17th Century are not suitable for deriving past values of the physical parameters of the solar wind.

Several problems contribute to difficulties in interpreting transient celestial phenomena as described in Chinese records. Frameworks are an overarching problem. Tianwen, the modern Chinese term for astronomy, in pre-modern times included meteorological phenonemena and was concerned with omenology. Manuscripts that include star charts and comets but also meteorological phenomena and omen reading texts were routinely reframed in modern scholarship to appear as if they included only astronomical content. The scope of pre-modern tianwen, however, was broader than its modern sense. Pre-modern celestial phenomena had political and religious significance. Apparent ambiguity arises from the presence of both meteorological and astronomical phenomena in a single category and from features of the classical Chinese language. Accounting for these problems is essential for research into transient phenomena using historical archives.

About 30,000 astronomical photographic plates were digitised between 2012–2017 with a special digitising machine that has high precision in both astrometry and photometry. All the images from the plates, together with plate information and measured coordinates of all the objects on the plates, have been stored in the Chinese Virtual Observatory.

We live in an age where an enormous amount of astrometric, photometric, asteroseismic, and spectroscopic data of Milky Way stars are being acquired, many orders of magnitude larger than about a decade ago. Thanks to the Gaia astrometric mission and followup ground-based spectroscopic surveys in the next 5-10 years about 10-20 Million stars will have accurate 6D kinematics and chemical composition measurements. KEPLER-2, PLATO, and TESS will provide asteroseismic ages for a good fraction of those. In this article we outline some outstanding problems concerning the formation and evolution of the Milky Way and argue that, due to the complexity of physical processes involved in the formation of disk galaxies, numerical simulations in the cosmological context are needed for the interpretation of Milky Way observations. We also discuss in some detail the formation of the Milky Way thick disk, chemodynamical models, and the effects of radial migration.

In this concluding article I recall the early history of the Gaia mission, showing that the original science case and expectations of wide community interest in Gaia data have been met. The quarter-century long partnership involving some 1,000 scientists, engineers and managers in industry and academia is delivering a large, high-quality and unique data set which will underpin astrophysics across many sub-fields for years to come.