Astronomy Digital Picture – 1/1000 seconds, ISO 80, 63mm f/8, on 21 Jan 2007 8:00AM, Bangalore.
22 Jan 2007
Our Sun is an averaged sized star, it contains approximately 99% of the total mass of the solar system. The Sun is close to perfect sphere, its polar diameter differs from its equatorial diameter by only 10 km. Its rotational period is 25 days at the equator and about 35 days at the poles.
The Sun does not have a definite boundary as rocky planets do, nor even a radius where the density suddenly begins to fall off; in its outer parts the density of its gases drops approximately exponentially with increasing distance from the center of the Sun.
The visible surface of the Sun, the photosphere (as seen in photo), is the layer below which the Sun becomes opaque to visible light. Above the photosphere visible sunlight is free to propagate into space, and its energy escapes the Sun entirely.
Tomorrow’s picture – Dhruva Nakshatra, the Pole Star.
Posted by naveenln 
Astronomy Digital Picture of the Day 