Look to the stars. You will notice that they are not all the same color. There is blue and white and yellow and orange and red. Why is it so?
To understand this, consider a light pocket flashlight. There, in a glass bubble, there is a thin metal thread. If the flashlight on, and the hair comes a bright white light.
This is because it passes through the electric current from the batteries. Here is the hair and heats up so that it begins to glow. But if the old battery, the flashlight shines much weaker. And if you look to thread his light bulb, you will see that the color has changed. Now it shines white and yellow.
Then orange. Then barely shines red. And finally, just goes out. This is because the current of the battery is reduced, and the thread is heating up all weaker.
Stars are huge balls of hot gases. But they're not the same. The hot glow of blue light. Those slightly cooler white. Colder - yellow. Then orange, red... In the end they go out the same way as a flashlight, the battery.
And brightness of the stars is also not the same. There are very bright, and there are those that you can barely see them.
In a very clear and moonless night sky can be seen faintly shining, whitish band. If traces of spilled milk. In ancient times thought that the goddess has spilled across the sky milk. And called the band of the Milky Way. But look at the milky Way with binoculars. You will see a whole lot of small and weak stars. Such weak that without binoculars and not make out. This is because they are very far from us.