How old is the earth?

Births are usually happy events -- attended by families and doctors and accompanied by baby showers and the like. For the Earth, however, it must have been rather lonely. We humans don't really know, however, because there were none of us around when the Earth was born. Scientists all over the world have data that indicates that the approximate age of the Earth is 4.5 billion years. That's 4,500,000,000 years! Considering her age, she's looking pretty good (aside from a few wrinkles the size of the Grand Canyon....ha....haha....).

Scientists have divided up this time into eras and epochs and periods to make studying such a vast time more manageable. The group of scientists who are responsible for setting up this time scale are called the International Commission on Stratigraphy. Stratigraphy is the study of the layers of rock on the earth, and how they can tell us about the past. Information is gained through the study of fossils, when and where they appear, the types of rocks found, and many other factors.

Here is a link to their current version, although a new one is due out soon:

Geologic Time Scale

If you like, you can also check your Earth Science Reference Tables for a great view of the history of the Earth. In the event that you have misplaced yours or don't keep them with you at all times (like you should!), here's a link where you can get your very own copy.

Earth Science Reference Tables

I keep a very small version in my wallet (with one of those little magnifying glasses) at all times...just in case. They're great at parties.