No hour-glass figure for our celestial neighbor. Instead, scientists have sat down with a detailed analysis of the shape of the moon and concluded it’s not a sphere. It has more of a lemon-shape. Don’t worry if you look at the moon, and wonder how in the world they came to that conclusion. It has everything to do with the moon’s crust.
Ian Garrick-Bethell, an assistant professor at UC Santa Cruz has a paper in the latest issue of Nature. The professor of Earth and planetary sciences looks at the shape of the moon, and how it was shaped from millions of asteroid impacts over the course of millions of years.
Scientists estimate that the Moon formed around 4 billion years ago, and was initially much closer to earth, spinning rapidly. The Moon eventually cooled and hardened into its present shape – slightly elongated with a bulge pointing towards Earth.
Thickness of its crust depends on where you are at on the Moon. It is thicker towards its equator, and as you stretch out towards the poles, it gets thinner.
In a statement, Garrick-Bethell explained the shape. “If you imagine spinning a water balloon, it will start to flatten at the poles and bulge at the equator. On top of that you have tides due to the gravitational pull of the Earth, and that creates sort of a lemon shape with the long axis of the lemon pointing at the Earth.”
He continued on saying that we are no longer looking at the primordial face of the moon. That face has long since shifted due to the impact zones removing some mass, and internal changes when the Moon was volcanically active.
The Moon has been getting a lot of press lately, with the three super-moons and the Opportunity Mars rover passing the distance record set by a lunar rover. For those astronomy lovers out there, stay tuned for the next super-moon in August. It promises to be the best one yet.