Satellites provide important data and services, such as communications, internet access, Earth observation, and technologies like GPS that provide positioning, navigation, and timing. However, the launch, operation, and disposal of an increasing number of satellites could cause or increase several potential effects, such as hindering optical and radio astronomy, creating additional space debris, and affecting the upper atmosphere through launch and reentry emissions. To help policymakers address the challenges presented by the ongoing increase of satellites in orbit, the U.S. Government Accountability Office (GAO) issued a report: Large Constellations of Satellites: Mitigating Environmental and Other Effects (GAO-22-105166). This keynote address discussed the report findings, including policy options directed to a range of policymakers that may include legislative bodies, government agencies, researchers, standards-setting organizations, industry, and other groups.

Hands-on observational astronomy is valued as one of the most important experiences by the alumni of the International Schools for Young Astronomers over the years. These are three-week long intensive schools that target specifically graduate students coming from astronomically underdeveloped countries and isolated groups. We recount our experience with observational tutoring that goes from a few nights to a few hours of observational experience. The thrill of discovery through the access to the telescopes is an experience difficult to transmit through database analysis alone. Even remote real-time observing has a beneficial experience for the students. We offer a selection of projects and the outcome this training has had over the years in the African continent.

The advent of innovative new radio telescopes and instruments around the world has enabled HI observations of galaxies that are sharper, deeper, fainter and farther than ever before. This paper provides an overview of the extragalactic HI landscape today, with a focus on large surveys with SKA pathfinder facilities. Ongoing work to measure structural properties of HI disks from the WALLABY survey on the ASKAP telescope is also summarised, with an emphasis on the challenges of building statistical samples of the marginally detected and resolved systems that are characteristic of widefield untargetted surveys. This work paves the way to map HI disks across cosmic time with the SKA.

Saturn’s magnetism and diamagnetism of ice can help explain the emergence of visible dense rings by transformation of the protoplanetary cloud containing ice bodies into a disk-shaped system of stable visible dense rings with extreme flatness at Saturn’s equator. It can also explain the thin structure of the rings as a whole, the sharp edges of dense rings, the existence and specific features of B-rings, and the stability of the entire dense ring system around Saturn. Additionally, it allows calculation of equilibrium separation of ice bodies, as predicted by J.C. Maxwell, with the magnetic repulsion of the ice bodies compensating for their gravitational attraction.

Over 30 years after the IAU Symposium 149 on Stellar Populations, we reconvened to reflect on significant advances in stellar population studies. Our discussions included the properties of stellar populations in the Milky Way, its satellites, as well as nearby and high-redshift galaxies. In particular, we highlighted the Milky Way’s role in our understanding of galaxy formation, and its relationship with what is being learnt from other galaxies. During a very busy week in Paraty, Brazil, we also discussed the community’s plans for the next decades while identifying key unresolved questions for further exploration. In addition to the scientific progress, we underscored the importance of fostering diversity within our field and ensuring that curiosity remains a driving force, embracing individuals from all backgrounds. This commitment to inclusion is vital for the continued advancement of research.

Strong solar flares and coronal mass ejections (CMEs) are prone to originate within and near active regions (ARs) with a high magnetic complexity. Therefore, to better understand the generation mechanism of flares and the resultant CME eruption and to gain insight into their stellar counterparts, it is crucial to reveal how solar flare-productive ARs are generated and developed. In this review, first, we summarize some general aspects of solar flares and key observational characteristics of such ARs. Then, we discuss a series of flux emergence simulations that were performed to elucidate the subsurface origins of their complexity and introduce state-of-the-art models that consider the effect of turbulent thermal convection. Future flare observations using SOLAR-C, a next-generation high-throughput extreme ultraviolet spectroscopy mission, are also discussed.

Cultural Astronomy is loosely defined as the study of humans and their relationship to the sky. With the movement to decolonize the curriculum and decolonize the academy happening in various parts of the world, academics along with students are co-creating new ways of being and learning. Inclusive astronomy can be seen as part of or adjacent to this movement, with its goals to transform astronomy to better attract and retain people embodying all types of diversity. This transformation has been framed largely as cultural with some efforts to augment rather than to transform the curriculum entirely. As a cultural astronomer, my research engages the transformation of astronomy both culturally and pedagogically. I will share how my research weaves and threads its way into creating a more inclusive astronomy (yes, I’m using intentionally gendered imagery!).

Astrobiology and SETI search for life-not-as-we-know-it (yet). Researchers aspire to an understanding not yet found. With that in mind, knowledge about three types of context can inform and improve the search. Observational context: knowing our location as humans (anthropism) can mitigate biases introduced by our desire to over-value humanity (anthropocentrism). Historical context: knowing the history of the search, not just the last 10–30 years, can clarify concepts and significance. Disciplinary context: understanding the rules by which different disciplines operate can reveal the limitations of a single perspective (astronomy, biology, ecology, sociology, law, medicine, philosophy, theology…). Astrobiology and SETI tell epic stories about the place of life in the cosmos. They locate humans morally as well as physically. We should ask why we tell them and how our context shapes the telling, because the stories shape human interactions with the world.

I describe the process for identifying the high level science goals of an observatory and the observing capabilities that it should provide in order to guide the project design work. Topics covered include the collection of science cases, development of technical requirements, including the qualities of the ideal site, and construction and operation considerations. Setting up the technical and scientific goals of the project in readiness for project promotion, rigorous project management and systems engineering practices is important for formally establishing a project.

We are in the age of the direct and indirect search for extraterrestrial life. The major question is: what are we looking for and to what extent can life on Earth provide an analogy for extraterrestrial life. We will address these questions by examining the emergence of life and its evolution through geological time, based on consideration of the Earth as an exoplanet. We conclude that, with the exception of a couple of hundred million years during the Great Oxydation Event 2.3-2.1 Ga, it would not have been possible for an extraterrestrial observer to detect traces of terrestrial life until the advent of planktonic eukaryotic algae after the Neoproterozoic Oxydation Event about 800 Ma. Thus, for most of the history of life on Earth, there would be no externally observable evidence of its existence. We address the implications of this for the search for extraterrestrial life.

As the number and variety of communications satellites proliferate in the rapidly accelerating New Space Age, specialists and lay observers alike have weighed the implications of a crowded orbital environment for astronomical research. Although so-called “megaconstellations” may be a relatively new development, conflict over the anticipated effects of space technology on astronomy has a much longer history, going back to the very first experimental communications satellites. Astronomers have long acted as environmental watchdogs for outer space even as the power landscape in the international aerospace industry shifted during the half century since Sputnik. What lessons might current astronomers take from past conflicts over the integrity of the night sky to address contemporary and future risk?

Atomic hydrogen (HI) gas is a key fuel reservoir for star formation in galaxies and provides an excellent tracer of their dynamical masses. The Square Kilometre Array (SKA) precursor observatories are already hinting at the incredible HI observations that we can expect from the SKA. We are also undergoing a quieter but equally exciting revolution in simulations of HI in galaxies. Up to now, we have had to resort to labelling HI in cosmological galaxy formation simulations in post-processing, subject to uncertain calibration and assumptions. New simulations are implementing cooling to 10 K and non-equilibrium ionization and chemistry, enabling on-the-fly calculation of HI fractions. We will soon have for the first time fully self-consistent, spatially-resolved predictions for the atomic hydrogen content, structure and kinematics of galaxies across cosmic history. I give an overview of the state of the art in simulation-based predictions for HI including recent breakthroughs and current challenges.

This study analyzes the motion of bodies ejected from the Earth or the Moon. We studied the ejection of bodies from several points on the Earth’s surface, as well as from the most far point of the Moon from the Sun. Different velocities and angles of ejection of bodies were considered. The dynamical lifetimes of bodies reached a few hundred million years. Over the entire considered time interval, the values of the probability of a collision of a body ejected from the Earth with the Earth were approximately 0.3, 0.2, and 0.15–0.2 at an ejection velocity υej equaled to 11.5, 12, and 14 km/s, respectively. At υej≤11.3 km/s, most of the ejected bodies fell back onto the Earth. The total number of bodies delivered to the Earth and Venus probably did not differ much. The probabilities of collisions of bodies with Mercury and Mars usually did not exceed 0.1 and 0.02, respectively. At υej ≥11.5 km/s, the probability of a collision of a body ejected from the Earth with the Moon was about 15–35 times less than that with the Earth, and it was about 0.01. The probability of a collision with the Earth for a body ejected from the Moon moving in its present orbit was about 0.3–0.32, 0.2–0.22, and 0.1–0.14 at υej =2.5 km/s, υej =5 km/s, and at 12≤ υej ≤16.4 km/s, respectively.

Beatriz Barbuy has made fundamental contributions to the study of stellar populations, from calibrating atomic and molecular line lists to establishing elemental abundances and isotopic ratios in different stellar populations of the Milky Way, particularly of the Galactic Bulge, providing thus important clues on how the Galaxy formed and how it was enriched over time. Furthermore, she has had a significant impact on the scientific community through organizing conferences and contributing through leading international roles, such as the vice-presidency of the International Astronomical Union. Her contribution to training young researches in stellar populations is also noteworthy, having supervised more than 20 PhD theses. Finally, her involvement in instrumentation projects, such as ESO’s VLT and ELT, is helping pave the way for new exciting discoveries.

Modern societies have an increasing number of technological developments which are shaping the structure and execution of daily duties. Communities with disabilities have historically experienced restricted access to many opportunities of study, work and leisure, but now the emergence of new resources and appliances is likely to increase the inequity gap unless actions against this are reinforced at different levels in the society. Every person, regardless of any aspect should have an equal right and opportunity to access, engage with and contribute to knowledge, participating actively in the decisions, institutions and processed, and making use of new technologies. Unfortunately, in many cases, access to this is not feasible because the frameworks for inclusive involvement and engagement are not being implemented or are not implemented in an appropriate way. This work highlights the importance to ensure inclusive participation in astronomy education, research and outreach, identifying the barriers preventing people with disabilities to engage and progress in all the aspects that are natural of our scientific field and underpinning the crucial actions that can foster equality, accessibility and inclusivity.

Despite the proliferation of solar and heliospheric observations, many questions regarding the nature and evolution of coronal mass ejections (CMEs) persist. We focus on exploring relationships between the three-dimensional characteristics of CMEs and their source region properties. We analyze the sources of a set of CMEs having polar position angles as seen from Earth, for which their morphological characteristics can be estimated with less uncertainties than typically possible. We rely on observations of different solar atmospheric regimes, provided by the STEREO, SOHO, and SDO missions. In the low corona and chromosphere, we characterize associated filaments and eruptive phenomena; while in the photosphere we investigate polarity inversion lines. The joint analysis of source regions and CMEs enables studying how the attributes of source regions impact the morphological and dynamical characteristics of CMEs, with implications for space weather forecasting and for the understanding of processes involved in the initiation and early evolution of CMEs.

This abstract explores the application of quantitative information theory measures and linguistic features to analyze animal communication systems and extends this methodology to contemplate the possibilities of interstellar communication as a part of CETI practice. We will assess some early findings by using information theory on social species with sophisticated acoustic communication abilities, such as bottlenose dolphins and humpback whales (Hanser, Sean F., et al.) as well as birds, as examples of how the complex interplay between notions, data, and misinterpretations can become established as reliable knowledge and cognition about and understanding of an ETI civilization and culture. The study also looks into the potential implications of extraterrestrial contact. Given the diversity of language instances in Earth’s evolutionary history, we discuss the choice of syntactic complexity of an “intelligent message” for potential alien civilizations. The central point of this paper is to examine the advantages and limitations of acoustic and visual communication, considering linguistical and mathematical constraints that may apply universally.

The increasing addition of meteor showers to the International Astronomical Union (IAU) list underscores the need for more accurate identification of new parent bodies, especially with the growing availability of video meteor data. Current methods using a high-threshold single-linking Dsh criterion often lack accuracy, prompting our study to explore advanced techniques for linking meteors to their parent bodies. Using the Moroccan meteor observation network as a foundation, we applied and compared several methods on the SonotaCo and EDMOND databases to detect new parent bodies. We further applied rigorous statistical tests to avoid random associations. This presentation highlights the network’s innovative methodology, its success in accurately tracing meteoroid origins, and its potential to predict impact zones on Earth (Guennoun et al.(2019)). Through collaborative efforts, this network provides a significant contribution in the study of meteor dynamics.