Earth Facts
The earth is about 4,600 million years old. For millions of years, its surface was covered by hot, liquid, rock. Gases and steam escaped from the fiery rocks to form the Earth's first atmosphere. The oldest known rocks are about 3,900 million years old. The oldest known fossils, about 3,500 million years old, are traces of simple organisms called bacteria. Early plants, growing in the seas 1,900 million years ago, gradually produced enough oxygen to make the air breathable.The Earth is not perfectly round but is slightly flattened at the poles and bulges a little just south of the Equator. The distance around the Equator is 40,075 km ( 24,902 miles ) while the distance around the Poles is 68 km ( 42 miles ) shorter.The Earth takes 365 days, 5 hours and 40 minutes to travel once in its orbit around the Sun.The distance between the Earth and the Sun is about 150 million km ( 93 million miles ).