The crossword solutions for the term EARTH'S CORE are ART. The EARTH's CORE is the innermost layer of the planet, located beneath the mantle and crust. It is composed of iron and nickel and is believed to be about 4, 000 miles in diameter. The CORE is divided into two parts: the inner CORE and the outer CORE. The inner CORE is solid and the outer CORE is liquid. The temperature of the CORE is estimated to be around 5, 400 degrees Celsius.