In Brief

5 July 2017

Our young moon’s supersonic winds made waves in its magma ocean

BILLIONS of years ago our moon had a magma ocean and a sodium atmosphere.

That’s according to a model created by a team including Prabal Saxena at the NASA Goddard Flight Center in Maryland. Saxena compares the early moon to a rock star: a metal-dominated thing that collapsed quickly and intensely.

Immediately after it formed, the moon’s surface was probably covered by a deep magma ocean. The top layers of this ocean would have been vaporised by the heat coming off Earth, which was still hot from a moon-forming impact. This created an atmosphere containing elements like sodium and silicon, which reached temperatures above 1700°C and would have been mostly on the Earth-facing side (

The difference in temperature and pressure between each side of the moon may have caused supersonic winds to blow from the Earth-facing side to the far side. The new model shows that the winds may have been strong enough to make waves in the magma ocean.


Sodium escaping the moon’s atmosphere could also help explain the mystery of why many moon rock samples have less sodium in them than Earth rocks.

This article appeared in print under the headline “Early moon had lopsided atmosphere”