ISRO Solar Mission: For the scientific community, Sun has forever generated an enigmatic interest as it is our closest Star (at the center of our Solar System), and has been the key to life on Earth, and continues to play a crucial role in Earth’s circadian and annual cycles.
Sun’s observational studies have been pursued in India for over a century by Kodaikanal Solar Observatory, set up in early 1900s and now run by Indian Institute of Astrophysics, Bengaluru. For last forty years, India also boasts of an exclusive lake island based Udaipur Solar Observatory, for Sun data.
Sun does not possess a fixed borderline since its density decreases exponentially with increasing height of the Solar disc, which is the visible surface of the Sun’s outer shell emitting light. The outer layers of the Sun, extending to thousands of km above Photosphere is called the Corona, which is truly enigmatic since it is million degrees Kelvin higher than approx. 6000K temperature of the Solar disc.