Stars and Galaxies: What Are Stars?

The video tutorial explains that the Sun is the closest star to Earth and is central to our solar system. It appears brighter and larger due to its proximity. The Sun, like other stars, is a hot ball of gases and plasma, emitting heat and light energy through chemical reactions. Astronomers study stars by analyzing their light energy. Distances in space are measured in kilometers for nearby objects and light-years for distant ones. Light travels at 310,000 km/s, covering 9.5 trillion km in a year. Proxima Centauri, the closest star beyond the Sun, is 4.3 light-years away, while Rigel is 910 light-years away, meaning its light takes 910 years to reach Earth.

How far is Proxima Centauri from Earth in light years?

What does it mean when we say that the light we see from Rigel left it 910 years ago?