Meleta Froehlich, age i4, of Sarasota, Fla., for her question;

How long has the earth existed?

A few generations ago, most experts thought that our lovely world was about 6400 years old. Then a lot of new facts were learned, and scientists realized that it is much, much oider. A lot of research has been done, but even now we cannot give the exact age of the earth. It is estimated to have existed for more than 3 billion years and perhaps almost as long as 4 billion years.

Science uses radioactive materials to date the rocks of the earth's crust. But it stands to reason that the oldest rocks have not been found. Also, the earth is likely to have been in existence before its first crustal rocks were formed.