Aditya – L1 First Indian mission to study the Sun. The Aditya-1 mission was conceived as a 400kg class satellite carrying one payload, the Visible Emission Line Coronagraph (VELC) and was planned to launch in an 800 km low earth orbit.   

• Satellite will be placed in the halo orbit around the Lagrangian point 1 (L1) of the Sun-Earth systems has the major advantage of continuously viewing the Sun without any occultation/ eclipses.   
• Therefore, the Aditya-1 mission has now been revised to “Aditya-L1 mission” and will be inserted in a halo orbit around the L1, which is 1.5 million km from the Earth.  The satellite carries additional six payloads with enhanced science scope and objectives.  

• The project is approved and the satellite will be launched during 2019 – 2020 timeframe by PSLV-XL from Sriharikota.  
• Aditya-1 was meant to observe only the solar corona.  The outer layers of the Sun, extending to thousands of km above the disc (photosphere) is termed as the corona.   
• It has a temperature of more than a million-degree Kelvin which is much higher than the solar disc temperature of around 6000K.  
• How the corona gets heated to such high temperatures is still an unanswered question in solar physics.  

Source: ISRO