What is Cosmic Rays

Our nearest shining star, the Sun, source of radiations and energy, sometimes generates severe events and phenomena in space which can affect our technology and biosphere. On the other hand, space weather, as defined by National Aeronautics and Space Administration (NASA), is conditions on the Sun and in the solar wind, magnetosphere, ionosphere, and thermosphere that can influence the performance and reliability of space-borne and ground-based technological systems and can endanger human life or health. A brief description of the Sun-Earth connection is firstly presented. Secondly, a particular attention is given to highlight the Sun's variability and the link between the space weather and climate change by means of some recent studies.