text: home work for my child "if there were no star what will happen to sky?"?   first, if that is an exact quote from the teacher, that teacher needs to proof read their work.  the only star that has a significant influence on our plane, and therefor our sky is the sun.  the sky generally refers to the atmosphere, which consists of different types of gasses: nitrogen, oxygen, water vapor and many others.  if the sun were to suddenly disappear it would get very cold very quick.  the temperature on the surface of the earth would fall to below -200 degrees celsius.  the gases in the atmosphere would all liquefy at this temperature, therefor what we refer to as the sky would exist no more.  we would be similar to the pseudo planet pluto.  one difference is that our planet does have a molten core that would add warmth to a degree that i can not guess.  to sum up:  without the sun, we would have a cold, dark planet with no atmosphere to speak of, therefor no sky.