HOW DOES A STAR FORM?

There are several steps in the formation of a star:
First a cloud of gas and dust comes together, due to gravity, to form a "protostar" (a hot blob that is not quite a star but will eventually become a star) that takes thousands of years.
Then the center of the blob becomes hot enough to give off visible light and most of the cloud of gas and dust has fallen into it. So now it looks like a star. That takes about a million years.
Then the rest of the cloud of gas and dust either falls into the star or gets blown away, and the star gets hotter and smaller due to gravity. Finally the center becomes so hot that the hydrogen gas starts to undergo nuclear reactions to become helium, which provides the energy for the star to keep shining for billions of years. It takes about 20 million years for the new star to get to this point.

USEFUL VOCABULARY:
- Blob: masa amorfa.
-Dust: polvo.