How do we know The structure and Age of the Earth

Earthquake waves reveal the Earth’s Structure There are three kinds of Seismic (Earthquake) Waves. They reflect and refract differently in the different layers of the Earth Scientists study them to determine the structure of the Earth

Radioactive Decay and “Half-Life” Large unstable (radioactive) atoms decay giving off radiation (energy) and becoming smaller more stable “daughter” atoms. Uranium becomes… Strontium Potassium becomes… Calcium and Argon Carbon 14 becomes… Carbon 12 The time it takes for half of the “mother” atoms to become “daughter” atoms is called the “Half-life” of the radioactive element.

The Age of the Earth and the Solar System By comparing the number of “mother” and “daughter” atoms the age of rocks is determined. The Oldest rocks on Earth are over 4 billion years old according to this method Thus the Earth is at least 4.5 billion years old Further some asteroid fragments found on Earth as meteorites have been dated as 4.6 billion years Making our Solar System at least that old.