There have been many climate fluctuations over the 10,000 years since Britain was last covered with an ice sheet. Advances and retreats of ice in the northern hemisphere during the past 500,000 years can be accounted for by changes in the warmth from the Sun.

This was caused by alterations in the Earth's orbit at periods of 96,000, 40,000 and 20,000 years.

Although that theory is widley accepted as a possible explanations for ice ages, it has not been proved. More than 50 theories have been put forward, but only a few have not been completely dismissed.

Not long ago a new theory was published in the science journal "Nature". According to Dr. Garry Hunt, of University College, intense radiations from the nuclear explosion of a nearby supernova - a star - could cause the destruction of part or all of the ozone layer and in this way trigger an ice age.

As for me, i like autumn best of all. The days become shorter and the nights longer. It isn't so hot in the day-time. The trees are covered with yellow and red leaves. At the end of summer apples, pears, plums and other fruit become ripe. In the South there are many oranges, peaches and tangerines. Autumn is plesant when it does not rain. General autumn is a rainy season of the year. When it rains the weather is nasty. The sky is covered with heavy clouds. It drizzles. It is muddy and wet.