  Gas pipelines, transmission lines, overhead wires, transformers, GNSS
navigation, and telecommunication systems are part of critical infrastructure.
Industry, transportation, service operations, farming, and everyday life highly
depend on this infrastructure. However, these systems are very sensitive to
solar activity. Therefore, all activities above are vulnerable and defenseless
against the catastrophic changes in Earth's cosmic environment. The Solar
System is dominated by the influence of our star. A small fraction of the
energy produced in the core of our star turns into a magnetic field and emits
the constant high-velocity flow, the solar wind. Solar magnetic activity
produces radiation and ejects matter from the upper atmosphere of our star. The
magnetic field of the solar wind interacts with the planetary magnetic fields
and atmospheres. These phenomena, called Space Weather have a serious influence
on the radiation environment of Earth where telecommunication, Global
Navigation Satellite System, meteorological, and other purpose satellites are
located. The conductivity and transparency of the higher partly ionized
atmospheric layer, the ionosphere also depend on solar radiation and activity.
This fact makes the navigation and communication systems dependent on solar
activity. Finally, the solar magnetic activity creates magnetic variations in
the terrestrial magnetic field and induces currents in gas pipelines,
transmission lines, overhead wires, and transformers. In this short briefing,
we introduce the solar activity phenomena, and their influence on our planet's
cosmic neighborhood and provide a detailed description of the Space Weather
effects on critical infrastructure. We describe the Hungarian national and
global space weather forecast centers and capabilities. Finally, we share some
guidelines on how to prepare for extreme space weather events.
