1. Stars
Matariki star cluster

2. What are stars?
A star is a huge sphere of very hot, glowing gas. Stars produce their own light and energy by a process called nuclear fusion.

3. How do we tell the difference between a star and a planet in the night sky?
A star twinkles, produces its own light and looks very small as it is very far away.
A planet glows, reflects light and looks bigger as it is closer.

4. What colour are stars?
Stars radiate light a little like glowing coals in a campfire.  Just as a glowing red-hot coal is cooler than a white-hot coal, for example, so a red star is cooler than a white star, and a white star is cooler than a blue star.   This was a major scientific discovery… simply by measuring the color of light coming from a star, and applying a little physics, it was possible to estimate a star’s surface temperature.

5. How big are stars?