How old is the Moon? see it here

This article was originally published on The Conversation. Read the original article.

Most scientists agree that the Earth has pretty much always had its moon. Details of the moon’s composition (in particular the “isotopic mixture” of heavier and lighter versions of various elements) are too similar to the Earth’s for it to have been captured from somewhere remote. However, some compositional details differ enough to rule out the idea that the moon is simply a chunk of the Earth that broke loose.
The details of how the moon formed, and when, have long been debated. Now two new studies shed fresh light on the process—even pinning down a date.
For more than 30 years, the prevailing view of the formation of our moon has been the “giant impact hypothesis”. The precursors to the current four rock planets—Mercury, Venus, Earth and Mars—appear to have been dozens of smaller bodies known as “planetary embryos”. According to the giant impact hypothesis, our moon formed as the result of the last of a series of “giant impact” mergers between planetary embryos that eventually formed the Earth. In this last collision, one embryo was nearly Earth-sized and the other approximately Mars-sized. The merged body resulting from this became the Earth. Debris flung out from the impact, most of which came from the rocky part of the smaller body, gathered in orbit to become the moon.
 On this basis, the birth of the solar system is generally accepted to have occurred close to 4.57 billion years ago. Scientists have long debated how long after this Earth’s moon-forming impact occurred. The “late school” favored 150-200m years after, whereas the “early school” favored a date less than about 100m years after the origin.