A star is a big, burning ball of gas in the universe. The following diagram shows a cross-section structure of a solar-type star:
Here are several interesting stars in the sky:
The Sun is the nearest star to the Earth.
The distance between the Sun and the Earth is changing periodically with an average of 149,600,000km, or 8.31 light minutes.
Proxima Centauri is the second nearest star, which is too small and too faint to be observable with the naked eye.
The distance from Proxima Centauri to the Earth is about 4.22 light years.
Sirius is the brightest star in the sky, which is about 8.6 light years away from the Earth.
Polaris, more commonly known as The North Star or simply North Star,
is the closest star to the North Celestial Pole.
Polaris stands almost motionless on the sky, and all the stars of the Northern sky appear to rotate around it.
