Abstract

Understanding the complexity inherent in collisionless plasmas (as encountered in space) is a fundamental problem in physics, but one which is also relevant to the high profile, multi-billion dollar business of space, a business which touches our everyday life in numerous ways, from the mundane, such as GPS units in cars, to the exotic, such as the trip of a lifetime on a suborbital rocket flight. However, it has become clear that the invisible link between the Sun and the Earth, mediated by the solar wind, results in a near-Earth space environment which can be hazardous for both robotic and human activities in space, and can also have a severe impact on our everyday life. As well as providing dramatic auroral displays, ‘space weather’ storms have caused power blackouts, the failure of radio communications, the loss of satellites, implementation of astronaut safety procedures on the International Space Station, and many other problems.

The main causes of variability in the near Earth space environment are briefly reviewed, followed by a discussion of recent advances in understanding the physics of magnetic reconnection; although many plasma phenomena contribute to space weather, reconnection is considered crucial because it enables the storage and explosive release of energy in both the solar corona and the Earth’s magnetosphere. This research is placed in context by describing a number of specific examples of space weather in more detail.

As society inexorably increases its dependence on space, the necessity of predicting and mitigating space weather will become ever more acute. This requires a deep understanding of the behavior of the plasmas that fill space and is prompting the development of a new generation of scientific space missions which we describe. We also speculate on the future exploitation and exploration of space and the role space weather will play.