REVIEW

First, read a short review the main ideas.

 I. Birth 

A Star begins as a cloud in space. Gravity pulls the cloud to its center. Heat and pressure build up in the center. The big cloud in space is called a nebula. It is made of mostly Hydrogen gas.

When too much pressure builds up in the cloud’s core, the Hydrogen start to stick together and explode. This is called nuclear fusion.

II. Stable Star

Gravity pushes in. Heat from the exploding center pushes out. These two forces balance, like a matched tug-of-war. The result is a round, stable star. Our sun is a typical star. The layers of a star are the core, radiation zone, convection zone, surface, and corona.

III. Death of Star

Hydrogen is the fuel for the nuclear explosions. When hydrogen is finally used up, gravity takes over. The star collapses and explodes. The sun will explode in 5 billion years.

QUESTIONS

1)  What is a star?

2)  What is our closest star?

I. Birth of a Star

3)  Describe how a star begins.

4)  What is a nebula?

5)  What is the nebula mainly made of?

6)  Which force pulls the nebula together? Why?

7)  What are three things which build up in the center of the shrinking cloud? Why? 

8)  When too much pressure builds up in the center, what starts to explode?

II. Stable Star

9)  Describe and explain how 4 hydrogen protons turn into one helium nucleus.

10)  What is nuclear fusion? 

11)  Describe a stable star.

12)  What happens in a star’s core? Why?

13)  What happens in a star’s radiation zone? Why do the hot gases rise?

14)  What happens in a star’s convection zone? Why does the gas rise up and then sink back down?

15)  What happens at the surface of the star? Why do the hot gases cool at the surface?

16)  Describe a star’s corona. Which colors of light are leaving the sun?

III. Death of a Star

17) Describe the death of a star. Why does the dying star collapse?

18) Why does the dying star explode?

19) What new things are made in an exploding star?

20) What happens to the star dust after the star dies?

21)  Where do the atoms in your body come from?

22)  Write 10 questions about stars and space.