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. That means it is a small body that revolves around it, just at he 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. Strangely 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 for it 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 14 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.

Fact File

Eclipses happen for a brief period when the Moon, Earth and Sun are in line. A lunar eclipse happens when the Earth lies between the Moon and the Sun, blocking off the light to the Moon, so that the Moon seems to vanish.

Why does the Moon follow us when we drive?

The Moon does not look as if it is very far away, but its distance from the Earth is about 239,000 miles. It is this great distance that explains why the Moon seems to follow us when we drive in a car and look up at it.

To begin with, our feeling that this is happening is just that, only a feeling, a psychological reaction. When we speed along a road, we notice that everything moves past us. Trees, houses, fences, the road – they all fly past us in the opposite direction. But when we look at the Moon we naturally expect it also to be flying past us, or at least to be moving backwards as we speed ahead. When this does not happen, we have the sensation that it is following us. In fact we could go along a straight path for miles and the angle at which we would see the Moon would basically be the same.

Fact File

The ebbing and flowing of tides are made by the Sun and Moon pulling on the oceans. When the Sun, Earth and Moon are in a line, there are large spring tides.

Why do stars die?

Stars are huge balls of burning gas that are scattered throughout the Universe. They burn for millions of years giving off both light and heat. Stars die when they eventually use up all their fuel and burn out. This process may take millions of years.

Towards the end of its life a star starts to run out of hydrogen to power its nuclear fusion. It starts to cool, becoming a red giant. The red giant swells and the pressure at its centre becomes so great that the star begins to absorb energy instead of emitting it. In a matter of seconds the star collapses, then explodes into a supernova. This is a huge explosion of light and energy that can be seen right across the galaxy.

Fact File

In the night sky, all stars appear to be the same size. In fact, they are all different sizes. Some are much bigger than the Sun; others are much smaller than the Earth. The most common stars are the same size as the Sun.

Asteroids

What is an asteroid? Asteroid (Greek for “star-like”) is the word used most for minor planets. The term asteroid is generally used to indicate a group of small celestial bodies that drift in the solar system in orbit around the Sun. The asteroid belt is a region of space between the orbits of Mars and Jupiter where most of the asteroids in our solar system are found orbiting the Sun. The asteroid belt probably contains millions of asteroids.

Astronomers think that the asteroid belt is made up of material that was never able to form into a planet, or of the remains of a planet which broke apart a very long time ago. The asteroids in the asteroid belt come in a variety of sizes. Some are very small (less than a mile across), while others are quite large. The largest asteroid is called Ceres. It is about one-quarter the size of our Moon.

We heard recently that an asteroid may come uncomfortably close to Earth in 2036. Astronomers are monitoring an asteroid named Apophis, which has a one-in-45,000 chance of striking Earth on 13 April 2036. Many astronauts, scientists and scientific centres are examining all the possibilities and I am sure that during the forthcoming 29 years we will be hearing more of Apophis and its fate!