LIGHT

The light speed is ( mind blowing ) 299 792 km per only a second. A light year is a distance it takes light to travel 1 year as the name says.If a star were to disappear it probably died before you were born , about a few 10000 years before you were born. You might be watching a star that died when looking at the sky. It is because it takes a lot of time for light reach to reach us.

Protons is what light is made from. Light doesn't weight anything which is the reason why it can travel so quickly and sorry to disappoint the SC-FI fans but it is impossible to travel at light speed as long as something has weight. It would take infinite amount of force to travel at light speed if an object has weight.