All terrestrial planets may have the same basic type of structure; such as a central metallic core, mostly iron, with a surrounding silicate mantle. The Moon is similar, but has a much smaller iron core. Io and Europa are also satellites that have internal structures similar to that of terrestrial planets.
Average ACT: 33. The average ACT score composite at Stanford is a 33. The 25th percentile ACT score is 31, and the 75th percentile ACT score is 34. In other words, a 31 places you below average, while a 34 will move you up to above average. There's no absolute ACT requirement at Stanford, but they really want to see at least a 31 to have a chance at being considered.
If you want to get in, the first thing to look at is the acceptance rate. This tells you how competitive the school is and how serious their requirements are. The acceptance rate at Stanford is 6%. For every 100 applicants, only 6 are admitted. This means the school is extremely selective. Meeting their GPA requirements and SAT/ACT requirements is very important to getting past their first round of filters and proving your academic preparation.