The Big Bang Theory

2. A famous scientist who studied space, time, and gravity.
4. A scientist who helped name the Big Bang Theory.
7. All types of light, including ones we can’t see like X-rays and radio waves.
9. The ability to do work or make things happen, like moving or giving off light or heat.
12. Faint heat left over from the Big Bang that scientists can still detect today.
15. A huge group of stars, dust, and gas held together by gravity.
17. When light looks more blue because objects are moving closer to us.
18. When light from objects in space looks more red because they are moving away from us.

1. All the colors of light we can see, like a rainbow.
3. A tool scientists use to study light and see what it is made of.
5. A scientist who helped discover leftover radiation from the Big Bang.
6. A scientist who worked with Penzias to find evidence of the Big Bang.
8. The study of space, stars, planets, and the universe.
10. The idea that the universe started a long time ago with a huge explosion and has been growing ever since.
11. A scientist who showed that the universe is expanding.
13. The lightest and most common gas in the universe; stars are mostly made of it.
14. Everything that exists, including all stars, planets, and space.
16. A very light gas found in the universe; it’s what makes balloons float.