1. Space Weather Major sources of space weather ● Solar wind – a stream of plasma consisting of high energy charged particles released from the upper atmosphere. ● Solar flares – sudden energy releases caused by the magnetic fields on the surface of the Sun which enhances the radiation ● Sunspots – the regions of strong magnetic fields cooler than the surroundings Space weather refers to the environmental changes within the solar system, particularly in the space surrounding the Earth, caused by the variable conditions on the Sun. The 11 year solar activity cycle influences the space weather, which can affect the functioning of the space-based and Earth-based technological systems and sometimes can even endanger life or health. Earth's magnetic field, mostly like that of a bar magnet offers some protection from the effects of the Sun. Because of its direct connection with the human activities, a lot of importance is given to the studies on space weather. Dedicated satellite continuously monitor the space weather. Coronal mass ejections – outbursts of plasma consisting of charged particles from the corona or the outer atmosphere of the Sun Earth's magnetic field The magnetic field in the solar wind directs the high energy particles towards the Earth. The Earth's magnetic field comes in the way between us and the Sun and protects us from the high energy streams. The ever present solar wind causes the Earth's magnetic field lines to compress on the side which is facing the Sun and expand on the side facing away from the Sun. Shock waves from the solar wind interacts with the Earth's magnetic field and causes temporary disturbances in the magnetosphere called as geomagnetic storms. The frequency of these geomagnetic storms vary with the solar activity cycle. Radiation hazards to human beings Very high energy particles released from strong solar flares can be hazardous to humans. Astronauts in space are exposed to high doses of radiation which can be potentially lethal. Earth's atmosphere and magnetosphere shield the humans at ground level. Damage to satellites Thousands of satellites go around Earth in their specified orbits. Geomagnetic storms causes these satellites to slow down due to an increased drag in the Earth's atmosphere. This further leads to a slight deviation in their orbits. Space weather may damage the electronic devices and might even result in its failure. Effects on navigation systems The global positioning system (GPS) is a space based satellite navigation system that provides location and time information in all weather conditions. GPSs are affected by the geomagnetic storms which bring about changes in the ionosphere, an electrically charged layer in the Earth's atmosphere. This leads to unaccounted delays in the GPS signals affecting its accuracy and availability. Disruption of power grids Geomagnetic storms result in electric currents in the magnetosphere and electrically charged ionosphere called geomagnetically induced currents. These currents disturb the overhead transmission lines, sometimes to the extent of damaging the components and causing electrical blackouts. Effect on radio communication High frequency radio waves are used by ships and aircrafts to communicate in remote areas far from the land such as over the oceans or poles. Space weather events can cause irregularities in the ionosphere that disturb the high frequency radio signals making the communication poor or impossible. Disturbances to GPS also makes it difficult for aircrafts to operate smoothly. Aurora Solar wind particles interact with the particles in the Earth's atmosphere giving rise to spectacular display of light called Aurora. Most auroras occur in a band known as the auroral zone, close to the geomagnetic poles. The auroras seen near the north pole are called Aurora Borealis or northern lights while those seen near the south pole are called Aurora Australis or southern lights. The Earth A schematic of the interaction between the solar wind and the Earth's magnetic field. http://www.iiap.res.in/ http://www.iiap.res.in/iiaoutreach/ Poster Credit: K. Sowmya