[Cincinatus]

Early runs tracked 3,000 pieces--leaving the iron core of the moon to be represented by just a single piece. Even the slightest computational imprecision could vastly overstate the iron content, in which case the computer compensated by reducing the impact angle. The result was a bias toward heavy impactors and light proto-Earths. Because Canup and Asphaug use 30,000 particles, they get by with a much smaller impactor. Everything--mass, iron, momentum--clicks into place.

Well, isn't that convienient? They just needed to simulate 30,000 particles, rather than 3,000. This -- for a process that actually involved trillions of particles.

Computer models of the "giant-impact hypothesis" for the origin of the moon are similar to computer models of global warming -- they can be tweaked to yield whatever answer you desire.

[JenB]

I feel silly, but what is a cryptomoon? (article reference Pluto's moon as a cryptomoon.) Anybody know? Sheesh, and I usually do really well with science stuff, and space trivia's my hobby...

[Sawdring]

I was waiting for Ken Ham to tell me how the Moon formed.

[Larry Lucido]

The young moon didn't take enough iron supplements.