As end-of-the-world scenarios go, an apocalyptic collision with an asteroid or comet is the new kid on the block, gaining respectability only in the last decade of the 20th century with the realisation that the dinosaurs had been wiped out by just such an impact. Now the science community is making up for lost time, with worldwide efforts to track the thousands of potentially hazardous near-Earth objects, and plans for high-tech hardware that could deflect an incoming object from a collision course – a procedure depicted, with little regard for scientific accuracy, in several Hollywood movies. Astrophysicist and science writer Andrew May disentangles fact from fiction in this fast-moving and entertaining account, covering the nature and history of comets and asteroids, the reason why some orbits are more hazardous than others, the devastating local and global effects that an impact event would produce, and – more optimistically – the way future space missions could avert a catastrophe.

This book explores the ponderomotive wave forces of space plasma, which have implications for a large number of cosmic plasma phenomena. Plasma is a state of matter comprising an equal amount of negative (electrons) and positive (ions) charged particles. The ionized state is the dominating state of matter in the cosmos for stars, galaxies and their corresponding intermediate regions. This book discusses the plasma state and its corresponding theoretical implications based on the analysis of space plasma data. The theory of ponderomotive forcing offers a most important tool for the analysis of “in situ” plasma data of acceleration processes in the terrestrial and Martian plasma environment. In addition, the solar wind interaction with objects in the solar system also provides a roadmap for the analysis and interpretations of other stellar and galactic objects, out of reach for direct “in-situ” measurements.

This volume is a compilation of the research presented at the International Asteroid Day workshop which was celebrated at Barcelona on June 30th, 2015. The proceedings discuss the beginning of a new era in the study and exploration of the solar system’s minor bodies. International Asteroid Day commemorates the Tunguska event of June 30th, 1908. The workshop’s goal was to promote the importance of dealing proactively with impact hazards from space. Multidisciplinary experts contributed to this discussion by describing the nature of comets and asteroids along with their offspring, meteoroids. New missions to return material samples of asteroids back to Earth such as Osiris-REx and Hayabusa 2, as well as projects like AIM and DART which will test impact deflection techniques for Potentially Hazardous Asteroids encounters were also covered. The proceedings include both an outreach level to popularize impact hazards and a scientific character which covers the latest knowledge on these topics, as well as offering proposals of promising new techniques that will help gain new insights of the properties of these challenging bodies by studying meteoroids and meteorites. Asteroids, comets, meteoroids and meteorites are introduced with descriptions of their nature, origin, and solar system pathways.

An asteroid or comet will inevitably strike the Earth some day, and potentially cause great destruction. This volume considers hazards due to collisions with cosmic objects, particularly in light of recent investigations of impacts by the authors. Each chapter, written by an expert, contains an overview of an aspect and new findings in the field. Coverage describes and numerically estimates the main hazardous effects.

The authors discuss such topics as "impacts with asteroids, the greenhouse effect, nuclear winter, fringe catastrophism, supernovae and an assessment of risks." (New Scientist).

Leading specialists in various disciplines were first invited to a multidisciplinary workshop funded by ICSU on the topic to gain a better appreciation and perspective on the subject of comet/asteroid impacts as viewed by different disciplines. This volume provides a necessary link between various disciplines and comet/asteroid impacts.