The Bible tells us that God created the earth in six days. Many scientists who have studied the earth and tried to measure its age have reached the conclusion that is approximately 4.5 billion years old. Most people accept the second view as being correct; they believe that scientists examine the evidence with an open mind and believe only those things which have been proven.
The late Carl Sagan wrote many books proving that the present state of the earth and the rest of the universe is the result of processes that took billions of years. He helped to produce a television series called Cosmos that was broadcast in 1980 and claimed to show how the universe developed.