4.5 billion years old 4.5 billion years old https://www.space.com/24854-how-old-is-earth.html Earth four-billion year old the earth's history 4.5 billion years old four-billion year old 4.5 billion years old planet's history https://www.space.com/24854-how-old-is-earth.html 4.54 billion years old 4.5 billion years old Earth's 4.5-billion-year history 4.54 billion years old five billion years Earth http://www.space.com... Space.com space.com Earth is about 4.54 approximately four-billion year old Earth 4.54 billion years old approximately 4.54 billion years old 4.5 billion years old http://www.space.com/24854-how-old-is-earth.html 4.5 billion years four-billion year old four and a half billion approximately How Old is Earth? Earth