The Sun drives a supersonic wind which inflates a giant plasma bubble in our very local interstellar neighborhood, the heliosphere. It is bathed in an extremely variable background of energetic ions and electrons which originate from a number of sources. Solar energetic particles (SEPs) are accelerated in the vicinity of the Sun, whereas shocks driven by solar disturbances are observed to accelerate energetic storm particles (ESPs). Moreover, a dilute population with a distinct composition forms the anomalous cosmic rays (ACRs) which are of a mixed interstellar-heliospheric origin. Particles are also accelerated at planetary bow shocks. We will present recent observations of energetic particles by Solar Orbiter and Parker Solar Probe, as well as other spacecraft that allow us to study the acceleration and transport of energetic particles at multiple locations in the inner heliosphere.

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.

Earth’s and Venus’ atmosphere mass and composition today are accumulated results of the solar hydrologic cycle over billions of years with comet collisions infusing gassy material onto the planets and solar wind blowing away the lighter gasses leaving primarily only carbon dioxide and nitrogen on both Earth and Venus. The comets entering the inner solar system have higher evaporation rate than collision probability, resulting in far less mass infusion onto inner planets than outer planets. The infused gasses onto the Earth are further processed by its chemical processes. Being too close to the Sun to have liquid water, Venus lacks chemical processes. The solar hydrologic cycle theory predicts comet mass infusion ratio between Venus and Earth to be 1:0.76. Comparing carbon dioxide and nitrogen mass in Venus atmosphere with nitrogen mass in Earth atmosphere plus carbon and nitrogen deposits in the crust, the ratio is 1:0.45-0.54.

We present an investigation of the Extreme-Ultraviolet (EUV) wave linked to the flare that occurred on 28 October 2021, along with the associated coronal loop oscillation and type II radio burst. The EUV wave was observed by multi-viewpoint with Solar Dynamics Observatory and Solar Terrestrial Relations Observatory – A. The associated coronal mass ejection (CME) was observed by Large Angle and Spectrometric Coronagraph (LASCO) as well by COR1 coronagraph. From the multi-view observation, we found that the EUV wave is propagated ahead of the connected CME. The coronal magnetic field measurement was performed by the coronal loop oscillations as well by the associated m-type II radio burst observations. We found the magnetic field strength values computed by both methods are consistence and are in the range of ≈ 5 to 10 G.

Coronal mass ejection (CME) often produces a soft X-ray (SXR) flare associated with the low-coronal reconnection and a type-II radio burst associated with an interplanetary (IP) CME-shock. SXR flares and type-II bursts outshine the background emission, making them sun-as-a-star observables. Though there exist SXR flare catalogs covering decades of observations, they do not provide the associated type-II luminosity. Besides, since radio burst emission could be beamed, the observed flux dynamic spectrum may vary with line of sight. Using long-term calibrated decameter-hectometric dynamic spectra from the Wind and STEREO spacecraft, we build a catalog of multi-vantage point observations of type-II bursts. Cross-matching with existing catalogs we compile the properties of the associated flare, reconnection, and the CME. Cross-correlation analysis was done between various parameters. Two novel metrics of flare and CME power show a strong correlation revealing a link between particle acceleration strengths in the low corona and IP space.

Coronal mass ejections (CMEs) profoundly impact space weather, necessitating a comprehensive understanding of their initiation and evolution in the solar corona. Solar Cycle 24 exhibited reduced sunspot numbers and heliospheric magnetic pressure compared to Solar Cycle 23, leading to increased weaker CME occurrences. Accurate forecasting relies on global magnetic parameters like those from SHARP datasets. We used MPI-AMRVAC to conduct numerical simulations employing the Breakout model in a multipolar magnetic field configuration embedded within a dipolar background. Shear-induced initiation of CMEs was studied to assess the influence of the global poloidal magnetic field on eruptions. Our research investigates the evolution of magnetic parameters under different scenarios (failed, single, multiple eruptions) by varying helicity injection. Findings suggest a stronger poloidal magnetic field inhibits CMEs, and the rate of absolute net current helicity may provide a clear picture of CME eruption.

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?

New apodization techniques are emerging rapidly to enhance the coronagraphs’ rejection capabilities and refine the optics for directly detecting exoplanets. One such technique, Interferometric Apodization by Homothety (IAH), involves splitting the incident Point Spread Function (PSF) into two using a 50 : 50 beamsplitter. One of the resulting PSFs has its amplitude reduced by a factor γ and its transverse dimension expanded by a factor ƞ. By combining these two PSFs, an apodized PSF is generated. In this study, we will use the standard values of γ and ƞ for both rectangular and circular apertures. We implement this approach in the laboratory using a Mach-Zehnder Interferometer with Cube Beamsplitters, chosen for their advantages over Plate Beamsplitters, including easy integration at a 0° angle of incidence and equal optical path lengths for reflected and transmitted light. This technique shows significant promise, achieving a contrast of approximately 5.10−3at small angular separations around 2.8 λ/D.

The search for extraterrestrial life, sapient or not, is a multi-phased process comprising pre-discovery, discovery, and post-discovery phases. Post-detection considerations can be conceptualized as contemplations of scientific and non-scientific issues pertinent partially to the discovery phase and to the final post-discovery phase that will be set in motion by a confirmed discovery of extraterrestrial life. To systematically explore the corresponding complex future landscape, scholars have proposed using alternative scenarios. However, this historical approach has actually focused more narrowly on generating specific detection situations, while neglecting the broader contextual environment scenarios that will necessarily encompass the detection. By drawing on Futures Studies, this work argues that a more comprehensive anticipatory approach is needed, involving the parallel delineation of both possible detection situations and possible future contextual scenarios, followed by their integration. Additionally, this work introduces a “Rehearsing Post-Detection Futures” workshop workflow inspired by the “Futures Literacy Laboratory” approach. This ready-to-deploy, interactive, participatory workshop is intended for educators and aims to help students and scholars in relevant disciplines broaden and diversify not only what but also how and why they anticipate when they consider the effects of a detection of extraterrestrial life in the future, particularly during the most urgent and precarious post-detection stage, i.e., the short-term stage right after the detection and its communication, thereby facilitating the cultivation of the participants’ futures literacy. Such interventions can support the mindful deployment of a critical-hermeneutic anticipatory perspective towards building a more responsible search for extraterrestrial life, sapient or not.

Expert working groups produced a number of thoughtful technical recommendations to policy makers and industry to mitigate the impact of satellite constellations on astronomical observations. The IAU CPS has undertaken to consolidate those complementary recommendations into a compact set, with advice to industry and policy makers, as well as identification of needs for further definition by the astronomy community.

One of the most important questions in the field of exoplanets is the impact that stellar CMEs (and their energetic particles) may have on exoplanetary atmospheres. This is of particular importance if the parent star is an M dwarf, since their powerful flares suggest (based on the solar analogy) that they will have commensurably powerful CMEs. Stellar CMEs have proved difficult to detect however, leading to the suggestion that the solar relationship between flares and CMEs does not extend down to the M dwarf regime. Two lines of evidence - both modelling of coronal evolution in response to flux emergence and surface transport and observations of the surface magnetic energy and helicity densities - point to the low surface differential rotation of M dwarfs as a possible culprit.

We are imaging Gaia-selected young massive white dwarfs in the 40 pc solar neighborhood with the ESO-VLT (ERIS LGS AO instrument) to search for >5 Jupiter mass companions. These white dwarfs have 2.5-5 M⊙ Main Sequence (MS) progenitors, and offer the unique possibility to test the formation of giant planets around intermediate mass stars, assuming these planets can survive post-MS evolution of their host stars. White dwarfs feature key advantages over their progenitor MS stars to spatially resolve giant planet companions in terms of (1) contrast and (2) angular separation. We limit ourselves to young white dwarfs with total ages (MS lifetime + white dwarf cooling age) < 1 Gyr which assures that any giant planets would be self-luminous and bright enough to be detectable (H-band < 25 mag). So far, we have obtained high angular resolution data for 10 white dwarfs with VLT/ERIS, with no confirmed detections, which might imply giant planets do not form around intermediate-mass MS stars, due to the rapid photoevaporation of their circumstellar disks caused by the host stars’ elevated FUV and X-ray irradiation. We keep searching.

With billions of planets in the galaxy, advanced civilizations could relocate planets within or into their planetary systems rather than destroy entire planetary systems to construct megastructures. Such shifts could create Strange Exoplanetary Architectures (SEA), with unusual planetary arrangements potentially indicating deliberate actions by extraterrestrial intelligence (ETI). Searching for biosignatures and technosignatures in these systems could be a promising method for detecting ETI activities.

This study addresses the growing concern in the astronomical community regarding the brightness and interference caused by low Earth orbit (LEO) communication satellites. Utilising data from a global network of telescopes and a custom Python pipeline, we analysed 369 observations of 159 OneWeb satellites obtained in the BVRI bandpasses with the Danish 1.54-metre telescope at ESO La Silla, Chile, revealing significant variations in brightness across different wavelengths and a substantial proportion exceeding recommended brightness limits. Our preliminary findings, incorporating diffuse sphere phase models, offer further insights into the satellite’s reflective properties and implications for future astronomical observations.

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.

This paper introduces the SETI Post-Detection Hub, its origins, motivations, and initial undertakings, as well as the rationale for such an endeavour - to explore and develop thorough and integrated approaches in preparation for a potential discovery event in the Search for Extraterrestrial Intelligence (SETI). Officially launched at the University of St Andrews in 2022, it brings together a highly multidisciplinary international team of experts.

From the outset, our rationale has been to weave together insights from diverse fields, including governance, impact strategies, analytics, and the humanities, with particular attention to the inclusion of all humanity’s cultural voices – a vital requirement to fully understand our challenge and its solutions. So, in preparation for the discovery of extraterrestrial life, the Hub will endeavour to grow readiness for complex futures by fostering a synergistic environment that encourages imaginative, methodical preparation, to stir transformative interdisciplinary and diverse engagement.

Coronal mass ejections (CMEs) are eruptive solar events with great influence on Earth. They often carry coherent magnetic fields in the form of magnetic clouds as they propagate through the heliosphere. Despite being large-scale structures, CMEs are subject to meso-scale dynamical processes such as turbulence and magnetic reconnection and exhibit fluctuations at many scales. A novel numerical approach is presented which separates the large-scale interplanetary motion of a CME from its local dynamics, investigating the effects of spherical expansion and turbulent fluctuations.

In this article, I analyze the claim that alien life could be “weird”. I propose to distinguish between two types of astrobiological weirdness: a naturalistic and an epistemic one. Weirdness, naturalistically construed, is an attribute for astrobiological traits. Weirdness, epistemically construed, is an attribute for scientific hypotheses and theories about the nature of such traits.

The prospect of human contact with extraterrestrial intelligence (ETI) carries profound societal implications, far surpassing the impact of discovering non-sentient microbes on distant planets. Such an encounter would reverberate throughout human society, challenging established beliefs, including theological doctrines, and reshaping our cosmic perspective. During the last decade, the search for extraterrestrial intelligence (SETI) and non-intelligent extraterrestrial life has received notable attention in digital media and newspapers and influenced public thoughts and perceptions about astrobiology, SETI and planetary science fields. This abstract takes a science communication and society perspective, evaluating our current decision-making processes and policies in anticipation of potential discoveries and their consequential interactions with varying forms of extraterrestrial life, including public attitudes, news dissemination and rumour control, and decoding and messaging ETIs.

As the number of large Earth-orbiting satellite networks (i.e., mega-constellations or mega-sats) increases, so does the threat posed to astronomical research. Bright satellite trails in exposures of the night sky can affect the quality of observations and hinder science objectives. Using the MASCARA station to detect satellites from the SpaceX Starlink network as a representative case, this study quantifies the present and future impact of mega-sats on ground-based optical astronomy. We find that further design revisions are required to mitigate the brightness concern of pre-Gen2 Starlinks and that hundreds of satellites could be visible in all-sky observations at peak observing times if additional measures are not taken.