The Life of Stars

Thanks to powerful telescopes, scientists have glimpsed new stars being born and ancient

stars dying. New stars form in a cloud of gas and dust called a nebula. As particles of gas

and dust churn around, gravity begins to pull together a clump of particles

into a ball. Gravity increases in the ball, and more and more

particles are pulled in. At the same time, the temperature

rises. If it gets hot enough, hydrogen will begin changing

into helium and releasing tremendous amounts of energy.

      

The massive and dense clump of particles will officially have become a star.

Stars live an extremely long time, but they don't live forever. In billions of years, the Sun will use up all of the hydrogen (its "fuel") in its core. It will become several thousand times brighter and expand to about 170 times its current size—about out to where Mars orbits now.