Jimmy Sheehan, age 9, of St. Catharines, Ontario, Canada, for his question:

WHAT IS IT LIKE AT THE CENTER OF THE EARTH?

The center of the earth is a huge, hot ball. Its outside edge is almost 2,000 miles straight down under your feet. Naturally, nobody has been down there to investigate on the spot. But there are certain tests that tell something about what the earth is like at the center. Most of this information comes from earthquakes because some of their shivering vibrations go on and on through the globe.

We know for sure that the center of the earth is made of very heavy materials and is very, very hot.  Scientists think that the thick outer layer may be 4,000 deg. Fahrenheit  which is hotter than a seething furnace. The inner core may be as hot as 9,000 deg. Experts suspect that the earth's entire core is made from extra heavy iron and nickel ¬and the temperature is hot enough to melt the mixture to form a sort of seething plastic.