Stars-Birth

Stars are born inside huge clouds of gas and dust.Some of these called giant molecular clouds,contain enough materials make a hundred thousand stars.If parts of the cloud are sufficiently dense and ,gravity will cause them to fall together.As an individual clump of gas and dust collapse,it heats up and,in time,becomes hot enough for nuclear reactions to begin.These reactions turn hydrogen into helium and turn mass into energy. Once these reactions  have started,the new arrival becomes a fully-fledged (or'main sequence')star.

the orion nebula

The orion Nebula,a glowing cloud of gas,is part of a huge star-forming region.It shines because it contains some very hot stars.Astronomers believe that more new stars are also being born behind the visible nebula.