WHAT IS CORONA?

The "CORONA" is the sun's thin external atmosphere. Sound waves & magnetic fields heat the gas in the corona to a temperature of over 1 million degrees celsius. This high temperature causes the corona to emit x-rays.However, it also emits a lot of light, which is why the corona can be seen with the naked eye when the sun's bright disc is covered,as is the case during a total eclipse of the sun. In order to observe the corona, space scientists use a special telescope,like the one aboard the solar and heliospheric observatory(SOHO) spacecraft, which has been fitted  with a device to cover the disc of the sun. The corona stretches several million kilometres in to space two or three times the diametre of the sun