Everything is born, one way or another. A plant is born when a seed drops into some soil that gets plenty of water and sunlight. A loaf of bread is born when you mix all the ingredients together and then bake it in the oven. A baby is born when . . . well, ask your parents. Stars are no different. They start from smaller elements and then go through a process that turns them into the bright shining lights we see in the sky. It's a little different than growing plants, baking bread, or having babies.
To make something new, all of the right ingredients have to come together somehow. Sometimes they are carried by the wind like seeds. Sometimes they are poured into a bowl like flour and yeast and water. In space, there is no wind and there are no bowls.
Gravity is the force that pulls things together. The bigger something is, the more it pulls. Things on Earth are drawn to each other for different reasons. People go to each other because they like each other. Bread ingredients come together because you mix them. Seeds land in soil if it's windy and they are lucky. Star stuff needs a lot of gravity to pulls it all into one place.
Mix flour, water, and yeast and you can start to make dough.
What begins as a lot of dust and rocks in space will start to pull together like ingredients poured into a bowl. There's no one up there to stir it all up, so gravity has to take care of this too.
Compression means to press together. What was spread out as flour and yeast and water is now all one mix of batter. What was dirt and water and seed is now all in one small place. What was a lot of dust floating all over the place is now all coming together and pushing into something harder. Finally, the plant, the bread, the parents, and the star have something in common. They all need heat.
Making bread dough is more work than I thought.
Anonymous friend of ElinorD, Public domain, via Wikimedia Commons
Wait, isn't it really cold in space? What's going to cook this star and light it up so that it burns like all the others in the sky? When all of this dust and rock starts to come together, they crash. They bang. They run into each other, push and rub so hard that everything gets super hot and melts together.
Star birth happens when all of the dust and gas melts together and heats up to make heat energy. When this happens, the stuff that was being pushed together by gravity is now going to start pushing back.
Dust and gas; just the right ingredients to make a star.
NASA, Public domain, via Wikimedia Commons
While gravity pulls in, the small parts that make the heat and light of a star make a lot of little explosions that push out.
Outward pressure is the force something gives when it is pushing out, and it's what makes the light and heat of a star. All of the stars you see in the night sky are just energy fighting against all of the gravity that's pulling them together. You can see the light of a star trying to grow up.
Stars are born just like everything else. All of the dust and rock come together with gravity. They push together into something hot and make heat by crashing into each other. This heat makes energy that pushes out and makes the light you see in the stars or the burning you see in our sun. A star never stops fighting once it has been born. It must fight against the thing that made it so it will not go away again. Just be glad your bread does not fight you after you've baked it.
References: Scientific American. "How is a star born?" Scientific American, 1999. <
http://www.scientificamerican.com/article.cfm?id=how-is-a-star-born>
NASA. "A Star is Born" NASA, 2010. <
http://www.jpl.nasa.gov/news/news.php?feature=584>