The Earth is exposed to constant outflow of the solar wind from the outer layers of the Sun, and violent transient events taking place from active regions increase the energy flux of both radiation and particles leaving the Sun. Thus the space surrounding the Earth is a highly dynamic environment that responds sensitively to changes in radiation, particles and magnetic field arriving from the Sun. Nowadays, it becomes increasingly important to understand how the physical system of Earth-space works and how the space around the Earth connects to interplanetary space. In the present paper we describe how explosive solar events, such as CME(Coronal Mass Ejection) and flares affect the Earth-space environment and how the space weather reacts to them. Practical consequences are presented to demonstrate why a broader view of Earth's environment is greatly needed to cope with modern day's inhabitation problem in a rapidly developing space age.

• 윤홍식(서울대학교 천문학과) | YUN HONG SIK (Department of Astronomy, Seoul National University)