Atmospheric escape is a fundamental phenomenon shaping the structure and evolution of planetary atmospheres. Physics of planetary winds range from global processes such as tidal interactions with the host star, through large-scale hydrodynamic outflow, to essentially microphysical kinetic effects, including Jeans-like escape and the interaction of planetary atmospheres with stellar winds and the own magnetic fields of planets. Each of these processes is expected to be most relevant for planets of different properties and at different stages in planetary and stellar evolution. Thus, it is expected that the hydrodynamic outflow guides the evolution of hydrogen-dominated atmospheres of planets having low masses (below that of Neptune) and/or close-in orbits, while the kinetic effects are most important for the long-term evolution of planets with secondary atmospheres, similar to the inner planets in the Solar System. Finally, each of these processes is affected by the interaction with stellar winds.

The Epoch of Reionisation (EoR) is the period within which the neutral universe transitioned to an ionised one. This period remains unobserved using low-frequency radio interferometers, which target the 21 cm signal of neutral hydrogen emitted in this era. The Murchison Widefield Array (MWA) radio telescope was built with the detection of this signal as one of its major science goals. One of the most significant challenges towards a successful detection is that of calibration, especially in the presence of the Earth’s ionosphere. By introducing refractive source shifts, distorting source shapes, and scintillating flux densities, the ionosphere is a major nuisance in low-frequency radio astronomy. We introduce sivio, a software tool developed for simulating observations of the MWA through different ionospheric conditions, which is estimated using thin screen approximation models and propagated into the visibilities. This enables us to directly assess the impact of the ionosphere on observed EoR data and the resulting power spectra. We show that the simulated data captures the dispersive behaviour of ionospheric effects. We show that the spatial structure of the simulated ionospheric media is accurately reconstructed either from the resultant source positional offsets or from parameters evaluated during the data calibration procedure. In turn, this will inform on the best strategies of identifying and efficiently eliminating ionospheric contamination in EoR data moving into the Square Kilometre Array era.

The Titan Haze Simulation (THS) experiment is a unique experimental platform that allows to simulate Titan’s complex atmospheric chemistry at low Titan-like temperature by generating a plasma discharge in the stream of a plasma jet expansion. Both gas and solid phase products are generated and can be analyzed using different in-situ and ex-situ diagnostics. Here, we present an overall description of the work accomplished with the THS in the last 10 years, our current research efforts, and the important implications for the analysis of Cassini’s returned data and preparation for future Titan missions.

Saturn’s moon Titan was explored by the Cassini mission for nearly 13 years. Important discoveries made during the Cassini mission include the observations of stratospheric clouds in Titan’s cold polar regions in which spectral features or organic molecules were detected in the infrared (<100 μm). In particular, benzene (C6H6) ice spectral signatures were recently detected at unexpectedly high altitudes over the South Pole. The combined experimental, modeling and observational effort presented here has been devised and executed in order to interpret these high altitude benzene observations. Our multi-disciplinary approach aims to understand and characterize the microphysics of benzene clouds in Titan’s South Pole.

Contamination due to foregrounds, calibration errors and ionospheric effects pose major challenges in detection of the cosmic 21 cm signal in various Epoch of Reionization (EoR) experiments. We present the results of a study of a field centered on 3C196 using LOFAR Low Band observations, where we quantify various wide field and calibration effects such as gain errors, polarized foregrounds, and ionospheric effects. We observe a ‘pitchfork’ structure in the power spectrum of the polarized intensity in delay-baseline space, which leaks into the modes beyond the instrumental horizon. We show that this structure arises due to strong instrumental polarization leakage (~30%) towards Cas A which is far away from primary field of view. We measure a small ionospheric diffractive scale towards CasA resembling pure Kolmogorov turbulence. Our work provides insights in understanding the nature of aforementioned effects and mitigating them in future Cosmic Dawn observations.

The Korean VLBI Network (KVN) is a unique millimeter VLBI system which is consisted of three 21 m telescopes with relatively short baselines. We present the preliminary results of simultaneous monitoring observations of the 22.2 GHz H2O and 43.1/42.8/86.2/129.3 GHz SiO masers based on the KVN Key Science Project (KSP). We obtained the astrometrically registered maps of the H2O and SiO masers toward nine evolved stars using the source frequency phase referencing method (SFPR). The SFPR maps of the H2O and SiO masers enabled us to investigate the spatial structure and kinematics from the SiO to H2O maser regions including the development of an outward motion from the ring-like or elliptical structures of SiO masers to the asymmetric structures of the 22.2 GHz H2O maser features. In particular, the 86.2/129.3 GHz SiO (v=1, J=2–1 and J=3–2) masers were clearly imaged toward several objects for the first time. The SiO v=1, J=3–2 maser shows different distributions compared to those of the SiO v=1, 2, J=1–0 and v=1, J=2–1 masers implying a different physical condition.

Ray tracing techniques have been used to investigate numerical effects on the propagation of acoustic waves in a non-hydrostatic dynamical core discretised using an Arakawa C-grid horizontal staggering of variables (Arakawa & Lamb 1977) and a Charney-Phillips vertical staggering of variables (Charney & Phillips 1953) with a semi-implicit timestepping scheme. It is found that the space discretisation places limits on resolvable wavenumbers and redirects the group velocity of waves towards the vertical. Wave amplitudes grow exponentially with height due to the decrease in the background density, which can cause instabilities in whole-atmosphere models. However, the inclusion of molecular viscosity and diffusion acts to damp the exponential growth of waves above about 150 km. This study aims to demonstrate the extent to which numerical wave propagation causes instabilities at high altitudes in atmosphere models, and how processes that damp the waves can improve these model’s stability.

The dry, cold, tenuous and stable air above the Antarctic Plateau provides superb conditions for the conduct of many classes of astronomical observations. We review in particular the rationale for undertaking near-IR, mm and particle astronomy in Antarctica, disciplines where telescopes are now operating at the US Amundsen-Scott South Pole Station.

Seeing measured in the open air with a differential image motion monitor (DIMM) is compared with seeing measured simultaneously at the Cassegrain focus of the Anglo-Australian Telescope (AAT). It is shown that when the mirror is hotter than the dome air, the AAT’s seeing is degraded by ~1 arcsec per Celsius degree of excess mirror temperature. The consequence of this is that mirror seeing currently contributes significantly to the seeing at the AAT on many nights. A mirror colder than the dome air does not seem to degrade seeing, and neither does an internal-to-external air temperature difference of up to at least 3°C when the venting fans are on.

The tropopause, typically at 16 to 18 km altitude at the lower latitudes, dips down to only 8 km in the polar regions, allowing access to the cold, dry and nonturbulent lower stratosphere by tethered aerostats. These can float as high as 12 km, have long operating lifetimes, and are extremely reliable. In contrast to free-flying balloons, they can stay on station for weeks at a time, and payloads can be safely recovered for maintenance and adjustment and relaunched in a matter of hours. We propose to use such a platform, located first near Fairbanks, Alaska, and later in the Antarctic, to operate a new-technology 4 m telescope with diffraction-limited performance in the near infrared. Thanks to the low ambient temperature (~200 K), thermal emission from the optics is of the same order as that of the zodiacal light in the 2–3 μm band. Since this wavelength interval is the darkest part of the zodiacal light spectrum from optical wavelengths to 100 μm, the combination of high-resolution images and a very dark sky make it the spectral region of choice for observing galaxies, QSOs and clusters of galaxies at the formation epoch of galaxies.

A knowledge of the on-ice seeing is a key requirement for planning future Antarctic observatories. In this paper we discuss the likely negative impact on seeing produced by the development of the deep winter surface temperature inversion (Ekman layer). The Automated Astronomical Site Testing Observatory (AASTO) will deploy, as one of its complement of site-testing instruments, an automated differential image motion monitor (DIMM) telescope designed to generate seeing data throughout the Antarctic winter. Here we describe the multi-aperture concept which has been developed for this mission, and touch upon some of the critical technological considerations associated with the low power budget and with the requirement of autonomous operation at very low temperature (–90°C).

The AURA Observatory site in northern Chile, which includes Cerro Tololo and Cerro Pachon, has been operational for over 50 years now, facing a variety of challenges to its long-term future. The site now hosts over 20 operational telescopes, ranging from small projects with 0.4m telescopes to the Blanco 4m, the SOAR 4.1m, and the 8m Gemini-South telescopes. In addition, we have recently begun the construction of the Large Synoptic Survey Telescope (LSST) on the summit of Cerro Pachon. We summarize our efforts over the past 20-30 years to highlight the importance of site protection through education and public outreach as well as through more recent promotion of IDA certifications in the region and support for the World Heritage initiatives described by others in this conference.

The importance of dark sky protection, potential threats to further degradation from LED technology, the announcement of a new world atlas of artificial night sky brightness, and the use of color images from the orbiting International Space Station for monitoring potential sources of light pollution were discussed in the six talks of this session. It was clear from the presentations that the work of professional astronomy depends upon continued restraint in the use of outdoor lighting, especially new LED technology, which relies upon blue-rich sources to support the advantages of high luminous efficacy and resulting energy savings.

This session opened with a crucial explanation by Michel Cotte of how astronomers first need to understand how to apply UNESCO World Heritage Criteria if they want to motivate their government(s) to make the case to UNESCO for World Heritage recognition. UNESCO World Heritage cannot be obtained just to protect dark skies.

Much more detail of this and the other presentations in this session, along with many images, can be found at the session website: http://www.noao.edu/education/IAUGA2015FM21.

The next speaker, John Hearnshaw, described the Aoraki Mackenzie International Dark Sky Reserve and the work it carries out . This was followed by a wide-ranging summary (by Dan Duriscoe and Nate Ament) of the U.S. National Park Service (NPS) Night Skies Program. The abstract of Cipriano's Marin's paper, “Developing Starlight connections with UNESCO sites through the Biosphere Smart" was shown in his absence. The final presentation (by Arkadiusz Berlicki, S. Kolomanksi and T. Mrozek) discussed the bi-national Izera Dark Sky Park.

Polarimetry is routinely used to characterise the surfaces of bodies in our solar system. In the near future, polarisation measurements of the starlight reflected by exoplanets will become a common and powerful tool to constrain the atmospheres and the surface properties of other worlds.

If extra-terrestial life has similar signatures as the life we know, then astronomical observations of planet Earth represent a benchmark to eventually probe bio-signatures also on other planets. In fact, linear polarisation spectra of Earthshine (the sunlight that has been first reflected by Earth and then reflected back to Earth by the Moon), allow us to detect the presence of oxygen, ozone, and water in the atmosphere of our planet. Surface properties such as fractional contributions of clouds and ocean, as well as vegetation can be inferred. Ultimately, Earthshine observations provide strong observational constraints on model predictions for Earth-like exoplanets.

In this contribution, we review the most recent observations of Earthshine by polarimetry. We highlight some advances in the interpretation and modelling of whole Earth polarisation, which will be of paramount importance to interpret possible bio-signatures of Earth-like planets in the habitable zone of nearby stars in the future.

Cosmic rays may be linked to the formation of volatiles necessary for prebiotic chemistry. We explore the effect of cosmic rays in a hydrogen-dominated atmosphere, as a proof-of-concept that ion–neutral chemistry may be important for modelling hydrogen-dominated atmospheres. In order to accomplish this, we utilize Monte Carlo cosmic ray transport models with particle energies of 106 eV<E<1012 eV in order to investigate the cosmic-ray enhancement of free electrons in substellar atmospheres. Ion–neutral chemistry is then applied to a Drift–Phoenix model of a free-floating giant gas planet. Our results suggest that the activation of ion–neutral chemistry in the upper atmosphere significantly enhances formation rates for various species, and we find that C2H2, C2H4, NH3, C6H6 and possibly C10H are enhanced in the upper atmospheres because of cosmic rays. Our results suggest a potential connection between cosmic-ray chemistry and the hazes observed in the upper atmospheres of various extrasolar planets. Chemi-ionization reactions are briefly discussed, as they may enhance the degree of ionization in the cloud layer.

Satellite cloud imagery is a standard tool of meteorology, and also of ground-based observational astronomy. Fast access to cloud imagery through the Internet now permits more accurate prediction of local cloud cover than was formerly the case. This is particularly useful for automatic and remotely operated telescopes, where an observer may be at a considerable distance from the telescope itself. Since satellite imagery can now be accessed through the Internet with such ease, direct reception of radio transmissions from weather satellites may seem unnecessary. However, advances in computing power and radio receiver technology permit simple automated receipt of satellite transmissions, particularly from the NOAA series of low Earth orbit satellites. This has the advantage of more up-to-date, and higher resolution, cloud imagery than can be obtained from the Internet. We have operated such a satellite receiving station since 2003 April, and have found it particularly useful when remotely operating our telescopes at Siding Spring Observatory (SSO). By automatically publishing our cloud imagery onto the World Wide Web we have established a resource that is widely used by other local observatories and by the general public.

In 1992 an NRAO 225-GHz site survey heterodyne radiometer was placed at the Geographical South Pole. The instrument operated over an entire annual cycle and provided direct measurements of the millimetre-wave sky brightness temperature as a function of zenith angle. Interpreted in a single-slab ‘skydip’ radiation transfer model of the atmosphere, these sky brightness measurements provided a time series of the millimetre atmospheric opacity. Statistics derived from this opacity time series were important for making comparisons with other candidate millimetre and sub-millimetre wave astronomy sites. This paper reexamines the 1992 measurements and the original analysis. Details of the skydip fit model, radiometer gain error, instrument stability, and a mid-season replacement to a window in the instrument enclosure combined to cause a modest under-reporting of the atmospheric opacity in previous reports. Unchanged are earlier conclusions that dry air makes a significant contribution to the total opacity at 225 GHz.

The near infrared sky spectral brightness has been measured at the South Pole with the Near Infrared Sky Monitor (NISM) throughout the 2001 winter season. The sky is found to be typically more than an order of magnitude darker than at temperate latitude sites, consistent with previous South Pole observations. Reliable robotic operation of the NISM, a low power, autonomous instrument, has been demonstrated throughout the Antarctic winter. Data analysis yields a median winter value of the 2.4μm (Kdark) sky spectral brightness of ˜120μJy arcsec−2 and an average of 210 ± 80μJy arcsec−2. The 75%, 50%, and 25% quartile values are 270 ± 100, 155 ± 60, and 80 ± 30μJy arcsec−2, respectively.

The Antarctic Plateau provides the best terrestrial sites for infrared (IR) and submillimetre (sub-mm) astronomy. In this paper we examine the relative importance of temperature, aerosol content and precipitable water vapour to determine which parameters have the greatest influence on atmospheric transmission and sky brightness. We use the atmospheric modelling program MODTRAN to model the observed sky spectrum at the South Pole from the near-IR to the sub-mm. We find that temperature and aerosol content determine the quality of near-IR observing conditions, aerosol content is the determining factor in the mid-IR up to 20 μm, while at longer wavelengths, including the sub-mm, it is the water vapour content that matters. Finding a location where aerosol levels are minimised is a key constraint in determining the optimum site on the Antarctic Plateau for an IR observatory.