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.

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.

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.

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?

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.

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.

As part of the mission of the International Astronomical Union Centre for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference (IAU-CPS) Policy Hub to consider national and international regulations about the usage and sustainability in outer space, we also included discussion specific to the rights of Indigenous peoples with respect to outer space under the context of the United Nations Declaration for the Rights of Indigenous Peoples (UNDRIP). In this work, we review how some of the articles of UNDRIP require various actors in the use and exploitation of outer space including satellite companies, nation states, and professional/academic astronomy to consult and support Indigenous peoples/nations and respect Indigenous sovereignties. This work is concluded with recommendations for consulting and collaborating with Indigenous peoples and recommendations for moving from the traditional colonial exploitation of outer space and building an anti-colonial future in relationship with outer space.

The discovery of phosphine in Venus’s atmosphere provides lessons for the search for life. The detection has survived all challenges and has acquired independent support from archival data from PVP. The presence of phosphine in Venus’ oxidising environment is perplexing, and comprehensive studies rule out all known abiotic sources. More data is needed to understand the origin of phosphine, leading to JCMT-Venus, a long term atmospheric monitoring programme. This can find how phosphine varies in relation to other species providing clues to its origin. We present the latest JCMT-Venus results. The discovery and subsequent papers were explicit that they did not constitute evidence for life, only of phosphine. Media and public reaction to the discovery and its implications provide lessons for future life searches, as does the reaction of the scientific community. How this was handled by the team, media, and general public will be reviewed.

Whether an exoplanet can retain its atmosphere is mainly controlled by the extreme-ultraviolet (EUV) radiation received from its host star, and the photo-chemistry in its outer atmosphere is driven by the far-ultraviolet radiation, primarily the hydrogen Lyman-α line, from its host star. Since interstellar hydrogen absorbs most of this EUV and Lyman-α radiation, there is a critical need for accurate reconstruction techniques to identify the intrinsic EUV and Lyman-α radiation that impacts the outer atmosphere of an exoplanet. This paper describes and critiques the available reconstruction techniques.

Commercial endeavours have already compromised our relationship with space. The Artemis Accords are creating a framework that will commercialize the Moon and further impact that relation. To confront that impact, a number of organizations have begun to develop new principles of sustainability in space, many of which are borne out of the capitalist and colonial frameworks that have harmed water, nature, peoples and more on Earth. Indigenous methodologies and ways of knowing offer different paths for living in relationship with space and the Moon. While Indigenous knowledges are not homogeneous, there are lessons we can use from some of common methods. In this talk we will review some Indigenous methodologies, including the concept of kinship and discuss how kinship can inform our actions both on Earth and in space.

This paper engages with the conference themes of community engagement and awareness raising, through proposing narratives which provide alternative stories to the belief in unrestricted technological development. The plan to launch up to 400,000 satellites into Earth orbit is an example of unregulated corporate capitalism: many private corporations and governments are encouraging rapid growth of the space sector without sufficient consideration of broader and potentially consequences for Earth and space environments or the interests and welfare of the wider community. My question in this paper is how far sustainability narratives from the humanities and social sciences can assist in the attempts to limit pollution of the sky and near-Earth environment.

The motion of planetesimals was studied in the Proxima Centauri and TRAPPIST 1 exoplanetary systems. The size of the feeding zone of planet Proxima Centauri c is discussed. It was noted that after hundreds of Myrs, some planetesimals could still move in elliptical resonant orbits inside the feeding zone of this planet that had been mainly cleared from planetesimals. The probability of a collision of a planetesimal initially located in the feeding zone of planet c with inner planet b was obtained to be about 0.0002 and 0.001 at initial eccentricity of orbits of planetesimals equal to 0.02 or 0.15, respectively. A lot of icy material and volatiles could be delivered from the icy zone near the orbit of planet c to inner planets b and d. The inclinations of orbits of 80% of the planetesimals that moved between 500 or 1200 AU from the star did not exceed 10°. It was obtained that several planets in the TRAPPIST-1 system accumulated planetesimals initially located at the same distance. Outer layers of neighbouring TRAPPIST-1 planets can include similar material.

A long-standing issue in astrobiology is whether planets orbiting the most abundant type of stars, M-dwarfs, can support liquid water and eventually life. Often previous studies have raised doubts for the habitability of planets orbting M-stars, due to the intense stellar activity during the early evolution. Those include solar-wind-like eruptions of the host star that could erode the planetary atmosphere, as well as the intense XUV radiation from the host. A new study shows that subglacial liquid water that accumulates on the night-side of tidally locked planets may provide an answer, significantly extending the habitability region, in particular around M-dwarf stars, which are also the most promising for biosignature detection with the present and near-future technology.

The characterisation of stellar magnetism of planetary host stars has increased momentum, especially for transmission spectroscopy investigations of exoplanets. Indeed, the magnetic field regulates how irradiated planets are, and the presence of inhomogeneities on the stellar surface hinder the precise extraction of the planetary atmospheric absorption signal. We are conducting a spectropolarimetric campaign to unveil the magnetic field properties of known exoplanet hosting stars included in the current list of Ariel targets. Here, we will focus on two of them: GJ 436 and HD 63433. The former hosts a warm-Neptune experiencing substantial atmospheric loss, modelled as a comet-like trail of hydrogen atoms. The latter hosts two sub-Neptunes and an Earth-sized planet that have likely experienced different atmospheric evolution paths. We reconstructed the stellar large-scale magnetic field via Zeeman-Doppler imaging, and used it as boundary condition to simulate the stellar magnetised wind and environment at the planetary orbits. For GJ 436, the planet motion is sub-Alfvénic, meaning that star-planet magnetic connections can occur. We derived the power released by star-planet interactions to be 1022 − 1023 erg/s, consistent with the upper limit of 1026 erg/s measured from ultraviolet lines. For HD63433, we identified 10% of the innermost planetary orbit as sub-Alfvénic, while the outer planets are outside the Alfvén surface, and a bow shock between the stellar wind and the planetary magnetosphere could form.

SatHub is one of the four hubs of the IAU Centre for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference (CPS). It focuses on observations, data analysis, software, and training materials to improve our understanding of the impact of satellite constellations on astronomy and observers worldwide. As a preface to more in-depth IAUS385 sessions, we gave a summary of some recent work by SatHub members and the current status of satellite constellations, including optical and radio observations. We shared how the audience can join or get more involved, e.g., via the CPS Slack for asynchronous collaboration. We also touched on what a future with hundreds of thousands of constellation satellites might look like.

How may life be defined? This is a question that has growing importance as humanity develops the ability to explore beyond the Earth and searches for evidence of life being present on other astronomical bodies from the planets and moons in our own solar system to the thousands of exoplanets we are detecting around other stars. Such a definition is non-trivial and, as we discover life in ever more diverse and ‘extreme’ environments on Earth broadening the regions of ‘habitability’, increasingly complex. In this short article, we review the different definitions of ‘life’, the need for such a definition and the implications that such a definition may have on the future development of astrobiology and the search for evidence of life in the universe.

Satellite constellation interference occurs across astronomical disciplines. We touch on the challenges for existing regulatory frameworks in radio astronomy, and present examples of interference from radio and γ-ray astronomy to optical and spectroscopic interference in ground-based and space-borne facilities. In particular, we discuss the impact of artificial satellites on the Hubble Space Telescope (HST), the High Energy Stereoscopic System (H.E.S.S.), an Imaging Atmospheric Cherenkov Telescope array, as well as possible mitigation strategies for the European Southern Observatory 4-metre Multi-Object Spectrograph Telescope (ESO 4MOST). Furthermore, we shed light on how ground-based optical telescopes such as the Oukaimeden Observatory contribute to IAU Centre for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference (IAU CPS) efforts that quantify satellite brightness.