because of carbon content in wood harms environment , although forest can be replenished but no one wanted to plant a tree in his/ her home. And also, cutting of woods causes environmental imbalances. Further, burning of wood causes a lot of pollution. Hence, it is advisable not to use wood as a fuel.
The gravitational pull of the Sun the interstellar dust attracting heat away from the protosun the process of nuclear fusion the nebular cloud condensing.
