earth and the moon's formation

Do we live on a thieving world? New research is proposing a new theory why rocks on the moon are similar to those on Earth but lack volatile material. Let’s back up in time and explore Earth and the moon’s creation.

In the early days of our solar system, a volatile-rich protoplanet was near present day Earth’s orbit. Most research point to a massive collision with another object, called Theia, and allowed the creation of the Earth and the moon as we know it today.

Most research has assumed vaporized material (volatiles), including water and other molecules, escaped what would become Earth’s moon and that’s why it lacks them.

Or maybe not. Researchers have published a new theory in the latest issue of Nature Geoscience. Robin Canup, the lead author out of the Southwest Research Institute in Colorado, explained a possible alternative.

It’s not just water rocks on the moon are lacking. Other volatile material such as zinc, potassium and sodium are included on the list. One theory is that the impact with Theia was so violent, it vaporized the volatile materials allowing them to escape the system.

earth and moon's volatile formation

One problem with that according to Canup and her team is the escape velocity needed to escape Earth’s gravity would have been to great. Instead, the materials would have been there for both to accumulate.

It turns out; the Earth could have been using its size to its advantage. The remaining volatile materials would have formed what would best be described as a Saturn-like ring system around the larger Earth.

Blame can also be placed on the moon’s orbit for its lack of volatile material. Since its formation, it has been moving steadily away from Earth. Today, it still inches away from us at a rate of 1.5 inches per year.

During its early years, it would have moved far enough away to lose the ability to grab material from the ring surrounding Earth. Instead of water and other molecules falling to the moon, the satellite’s gravity helped push them to our planet.

The study not only presented an alternative in our understanding of the Earth and the moon but notched another first. The research team combined heat and chemistry models with models of motion for the first time. Also, the chemistry models were developed to account for an oxygen-dominated disk that would have surrounded a forming Earth.

It’s a fascinating study and worth a read. Was our planet a thief? Maybe. In the case of planetary formation, size counts for something.


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