| A | B |
|---|
| Big Bang | start of the Universe |
| galaxy | billions of stars |
| nuclear fusion | how stars release energy |
| hydrogen | main fuel for a star |
| Milky Way | "our" galaxy |
| parallax | apparent shift in star position as we orbit |
| cosmic background radiation | overall "hiss" ; evidence for Big Bang |
| seafloor spreading | makes magnetic stripes ; evidence of continental drift |
| plate tectonics | what drives continental drift |
| erosion | wearing away of rocks |
| earthquakes | caused by plates slipping past one another |
| mountain building | caused by plates colliding |
| meteor | asteroid entering our atmosphere as shooting star |
| meteorite | meteor which lands on Earth |
| asteroid | mini-planet |
| crust | outer layer of Earth |
| sedimentary rock | rock built up in layers over millions of years |
| Wegener | he put forward idea of continental drift |
| Sun | our nearest star |
| mass extinction | probably caused by meteorite impact |
