Corona
The thin layer of air around the sun is called the corona. The corona is the outermost layer of the sun's atmosphere and is composed of extremely hot ionized gas. It is only visible during a total solar eclipse when the moon blocks out the bright light of the sun, allowing the fainter corona to be seen.

Characteristics of the Corona:
- The corona has a temperature of over a million degrees Celsius, much hotter than the surface of the sun.
- It extends millions of kilometers into space and is most easily seen during a total solar eclipse when it forms a beautiful halo around the sun.

Importance of the Corona:
- Studying the corona is important for understanding solar phenomena such as solar winds, solar flares, and coronal mass ejections.
- The corona plays a crucial role in the sun's magnetic field and influences space weather around the Earth.

Observing the Corona:
- Scientists use specialized instruments like coronagraphs to observe the corona without the need for a total solar eclipse.
- Space missions like NASA's Solar and Heliospheric Observatory (SOHO) provide valuable data on the corona's behavior and dynamics.
In conclusion, the corona is a fascinating and important part of the sun's atmosphere, and studying it helps us better understand the sun and its impact on our solar system.