According to this theory, the Sun and all the planets of our Solar System began as a giant cloud of molecular gas and dust<span>.</span>
This is possible because when a star dies, it basically expands to its maximum (explodes). Therefore, the materials of the exploded star mix with the primeval hydrogen of the Universe. Later, other stars are formed out of this mixture. Thats also how the sun was formed. :)
The biosphere. This is the layer that contains all life on the planet.
Plants<span> respire all the time </span>because<span> their cells need the energy to stay alive, </span>but plants can<span> </span>only<span> photosynthesize when they are in the light</span>
