What is the scientific notation for earth

Earth: radius = 6378 kilometer, diameter = 12756 kilometers.

For example the age of the Earth (see above) can be written as 4.6 X 109 years. This means that this number has 9 places after the decimal place - filled with zeros unless a number comes after the decimal when writing scientific notation. So 4.6 X 109 years represents 4600000000 years.