Why does the moon shine?
There is no mystery at all as to why the Moon shines. The Moon is a satellite of the Earth. This mean it is a small body that revolves around it, just as the Earth revolves around the Sun.
The only reason we can see the Moon from Earth, or that it appears to ‘shine’, is because light from the Sun strikes its surface and is reflected to us. Strange enough, we can only see one side of the Moon from the Earth. This is because the Moon rotates on its axis in the same length of time it takes to make its journey around the Earth.
Since the Moon has no atmosphere, or air, the light from the Sun causes rather interesting effects. For about fourteen days, the surface of the Moon is heated by the direct rays of the Sun to a temperature above that of boiling water. The other half of the lunar month, it is exposed to the cold of a long, dark night.
Why do stars twinkle?
Most stars burn steadily and if we could see them from space they would not actually be twinkling at all.
As the light from a star passes through the Earth’s atmosphere, it is bent by changes in the air temperature. This makes the light appear to flicker. Because of this effect observatories for studying the stars are situated on mountain-tops. The reason for this is because the higher up you go, the air becomes thinner and it is less likely to cause the twinkling effect.
Do you know that a galaxy is an enormous group of stars which is held together by the force of gravity? Our own galaxy is called the Milky Way and this is in the shape of a spiral. There are possibly as many as 100 billion galaxies in the universe. Any of them are grouped together in clusters with huge areas of space between them and consequently form many irregular shapes.