As I research the moon in order to add some verisimilitude to my story, I am coming across fascinating theories and facts that I had no idea existed. One such discovery is the existences of mascons (Mass Concentrations) that intensify the moon’s gravity over several lunar Mares such as the Sea of Serendipity or the Mare Imbrium.

Here is a map of the Moon’s gravity – click here to see a larger version:

Earth’s gravitational pull is about 980 mGals (things accelerate towards the Earth at the speed of 9.8 meters/second), and can vary slightly as one moves about; you weigh, for example, fractionally heavier in Algeria than you do in India.

Gravity on the moon is generally agreed to average at about 1/6th that of Earth’s. So while I may weigh 175lbs here, I would way just a little under 30lbs on the moon. It isn’t quite that simple, however: about twelve sites have been detected on the moon using Doppler scanning (the technology is beyond me) that show an increase in lunar gravity to almost half that of Earth’s. Thus while I may 1 pound heavier in Algeria than I would in India, I would more than double my weight if I moved from the peaks that surround the Sea of Serenity to the lowland plains.

The cause for this radical change in gravitational pull is not completely understood. Scientists believe that they could have been caused by meteor impacts that superheated the lunar crust and allowed basalt to rush up and form a massively dense ‘plug’ just below the surface hundreds of kilometers wide. This incredibly dense material would then distort the gravitational field directly above it.

Here is a simulation of the topography (top) versus the gravitational field (bottom) of the Sea of Serenity:

So – in short – how cool is that? There’s even a place on the moon where the strength of the gravity changes like ripples on the surface of a pond. The Mare Orientale has a small mascon in its center surrounded by a negative ring, which is surrounded in turn by a positive ring. You would gain and lose weight as you approached the center of the Mare’s basin, and there’s evidence that this phenomenon may occur around the other mascons as well.

The problem with learning all this cool information is that I suddenly want to weave it into my story, but need to do so without grinding the tale to a halt as I indulge in excited exposition. Next I’ll talk about the Interplanetary Transport Network, or maybe the Peaks of Eternal Light!