| A | B |
|---|
| nuclear fusion | takes place at 15,000,000 degrees celsius |
| neutron stars | rapidly spinning stars which emit radio waves |
| stars | glowing balls of gas |
| planetary nebulae | ring around the core of a star |
| x-ray | form of energy coming from black holes |
| helium | nuclear fusion converts hydrogen into this element |
| carbon atoms | fusion of helium atoms form these |
| pulsars | they give off pulses of radio waves |
| core | area of the cloud in which nuclear fusion takes place |
