The orbiter of Chandrayaan 2, that has been rotating around the Moon, observed a series of small flares from the Sun on September 30. This observation was possible with the help of X-rays emitted by the Sun. The orbiter of Chandrayaan 2 uses two instruments to measure such phenomena. It was initially installed in the ship to measure the lunar elemental composition using the X-rays emitted by the Sun; however, it has detected the solar flares of the sun now. As the Vikram lander failed to make a soft landing on September 7, the Chandrayaan 2 mission launched by the Indian Space Research Organisation (ISRO) has been 98% successful and the orbiter of the spacecraft continues to revolve around the Moon.
According to an official release by ISRO, “Chandrayaan-2 orbiter utilises X-rays emitted by the Sun in a clever way to study elements on the lunar surface. Solar X-rays excite atoms of constituent elements on the lunar surface. These atoms when de-excited emit their characteristic X-rays (a fingerprint of each atom). By detecting these characteristic X-rays, it becomes possible to identify various major elements of the lunar surface. However, in order to determine their concentration, it is essential to have simultaneous knowledge of the incident solar X-ray spectrum.”
As per ISRO, the Chandrayaan-2 orbiter carries two instruments, Chandrayaan 2 Large Area Soft X-ray Spectrometer (CLASS) and Solar X-ray Monitor (XSM). These instruments are used to measure the lunar elemental composition using these instruments. ISRO in its official statement explains, “The CLASS payload detects the characteristic lines from the lunar surface and the XSM payload simultaneously measures the solar X-ray spectrum.”
The Sun’s surface is very active and many violent phenomena continuously keep occurring on it. The atmosphere of the Sun, called corona is also equally active. These activities occurring on Sun’s surface follows an eleven-year cycle, which means, it goes through its 'solar maxima' and 'solar minima' once every eleven years. ISRO explains that “while the cumulative emission of solar X-rays emitted over a year varies with the solar cycle, these are often punctuated with extremely large x-ray intensity variations over very short periods, few minutes to hours. Such episodes are known as solar flares.”