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'What does all this stuff about flying saucers amount to? What can it mean? What is the truth?' Winston Churchill, prime minister's personal minute, 28th July 1952 The UFO Files tells the story of over 100 years of UFO sightings, drawing on formerly secret government documents at the National Archives in London. Alongside extraordinary reports by ordinary people, it reveals details of official interest and investigations stretching back more than 80 years. In this remarkable book, fully updated for this second edition, David Clarke reveals an array of startling stories from possible UFO reports hidden among Met Office investigations of aerial phenomena in the 1920s to the conclusions of Project Condign, the secret British Intelligence UFO study completed in 2000. As well as covering Roswell and Britain's own Rendlesham Forest mystery, Clarke raids the records for dramatic stories of abductions and close encounters, ghost aircraft and crop circles, and UFO reports by both civilian aircrew and military personnel. Dramatic witness statements and interviews combine with rarely seen photographs, drawings and newly available documents to offer a unique guide to one of our most intriguing mysteries.

Since its emergence in the 1960s, belief in alien abduction has saturated popular culture, with the ubiquitous image of the almond-eyed alien appearing on everything from bumper stickers to bars of soap. Drawing on interviews with alleged abductees from the New York area, Bridget Brown suggests a new way for people to think about the alien phenomenon, one that is concerned not with establishing whether aliens actually exist, but with understanding what belief in aliens in America may tell us about our changing understanding of ourselves and our place in the world. They Know Us Better Than We Know Ourselves looks at how the belief in abduction by extraterrestrials is constituted by and through popular discourse and the images provided by print, film, and television. Brown contends that the abduction phenomenon is symptomatic of a period during which people have come to feel increasingly divested of the ability to know what is real or true about themselves and the world in which they live. The alien abduction phenomenon helps us think about how people who feel left out create their own stories and fashion truths that square with their own experience of the world.

The Impact Monitoring (IM) of Near Earth Objects (NEOs) is a fundamental part of the planetary defense strategy. Current NEO IM systems (Aegis, NEODyS and Sentry) scan the Confidence Region (CR) of each observed object looking for Virtual Impactors (VIs) with a time horizon of about 100 years. This procedure is performed regardless of the uncertainty with which the orbit of the object is known, and without considering whether a scattering encounter is present in the propagation time span. In view of the likely future increase of the IM workload due to higher future NEO discovery rates, it might be more reasonable to adapt the predictability horizon of the impacts to each object, taking into account the orbit uncertainty and the close encounters experienced. In this paper we discuss the problem of estimating a reasonable predictability horizon when multiple close encounters are present and start to address the problem proposing a formal mathematical definition of scattering encounter.

In this paper, we study the limits of application of canonical perturbation theory, specifically the validity of the normal form approximations, for the study of the mean motion resonances of the planar circular restricted three-body problem in the domain of orbits which cross, or are close to cross, the orbit of the secondary body. First, we discuss analytic issues related to the definition of a MMR normal form within a domain of the phase-space to which these orbits belong; then, we compute with a numerical method the canonical transformations defining the MMR normal forms. The limits of validity of the averaging method are studied by supplementing the information provided by the phase-portrait representations of the normal form Hamiltonian with analyses concerning the preservation of the quasi-integrals of motion obtained through one step of perturbation theory, and the computation of fast Lyapunov indicators regularized with respect to the close encounters with the secondary body. We provide numerical explorations using as model examples the external 1:2 and 5:6 MMRs for values of the mass ratios which are representative of the Sun–Jupiter and Sun–Neptune cases. For the 1:2 MMR, the efficacy of the averaging method is established also for chaotic orbits of eccentricity up to e∼0.55.

A method for the nonlinear propagation of uncertainties in Celestial Mechanics based on differential algebra is presented. The arbitrary order Taylor expansion of the flow of ordinary differential equations with respect to the initial condition delivered by differential algebra is exploited to implement an accurate and computationally efficient Monte Carlo algorithm, in which thousands of pointwise integrations are substituted by polynomial evaluations. The algorithm is applied to study the close encounter of asteroid Apophis with our planet in 2029. To this aim, we first compute the high order Taylor expansion of Apophis’ close encounter distance from the Earth by means of map inversion and composition; then we run the proposed Monte Carlo algorithm to perform the statistical analysis.

Broken down in the Sahara Desert, a pilot meets an extraordinary Little Prince, travelling across time and space to bring peace to his warring planet. Inua Ellams' magical retelling of the much loved story by Antoine de Saint-Exupéry turns the Little Prince into a descendant of an African race in a parallel galaxy. His journey as a galactic emigrant takes us through solar systems of odd planets with strange beings, addresses climate change and morality, and shows how even a little thing can make a big difference.

This research note reports on whale interactions in northern Norway and asks: How are close encounters not in line with good practices of whale watching represented and discussed in the online sources accessible by tourists and recreationists? Based on an exploratory qualitative investigation of critical episodes of close encounters with cetaceans, this article identifies some main aspects emerging from the online representations and discussions at various levels (local, national, international). The findings suggest some important points of reflections for future developments of whale watching in northern Norway as well as worldwide.

The extension of Öpik’s theory of close encounters developed in the last decades allows a fully analytical, quantitative treatment of the motion of a small body encountering a massive perturber on a circular orbit. In this paper we derive explicit expressions for the initial values of the angular elements of the small body orbit, of given semimajor axis, eccentricity and inclination, in order to obtain a post-encounter orbit with prescribed values of semimajor axis, eccentricity and inclination. We describe the geometrical aspects of the algorithm, and give two examples of application; the first of them concerns the geometry of the 2029 Earth encounter of Apophis, while the second illustrates a sequence of close encounters with Callisto of the JUICE probe, aimed at changing the inclination of the spacecraft orbit. In the planning of complex space missions involving multiple encounters with planets or satellites, the algorithm described in the paper could provide a reliable initial guess to start the computationally intensive optimization process.

We consider the effect of an asteroid’s approach to a planet on its rotational dynamics by means of comprehensive numerical experiments. For a number of asteroids experiencing successive approaches to several terrestrial planets, characteristic estimates of the change in the asteroid’s proper rotation period due to the approach to the planet are obtained. The rotational dynamics of the asteroid (367943) Duende during its very close approach to the Earth in 2013 is considered, and estimates of the asteroid’s possible rotation speed up to the moment of approach are obtained.

Close planetary encounters play an important role in the evolution of the orbits of small Solar system bodies and are usually studied with the help of numerical integrations. Here we study close encounters in the framework of an analytic theory, focusing on the so-called b-plane, which is the plane centred on the planet and perpendicular to the planetocentric velocity at infinity of the small body. As shown in previous papers, it is possible to identify the initial conditions on the b-plane that lead to post-encounter orbits of given semimajor axis. In this paper we exploit analytical relationships between b-plane coordinates and pre-encounter orbital elements and compute the probability of transition to these post-encounter states, and numerically check the validity of the analytic approach.