Moonbuilder

The simulation moonbuilder.gsim simulates the formation two moons around the Earth. The simulation begins with 100 moonlets in Earth orbit. Each moonlet has a diameter of 940 km, and a mass that is 1/50 that of Earth's real moon. Their orbits have semi-major axes between 25,000 km and 75,000 km.

All collisions are elastic collisions, where the kinetic energy of the moonlets is conserved. All moonlets that collided merge into a single larger moonlet.

Download moonbuilder.gsim

(You need to have the program Gravity Simulator installed on your computer first. Click Here to download Gravity Simulator.)


The simulation begins on January 1, 2005. 100 moonlets orbit the Earth.


After 2 days, many of the moonlets have merged to form larger moonlets.


10 days after the beginning of the simulation, the mergers continue.


After 1 month, only 3 moonlets remain. Combined, they contain all the mass of the original 100 moonlets.


Six weeks later, the smallest of the 3 remaining moonlets is ejected into interplanetary space.


The two remaining moonlets settle into stable orbits around the Earth.