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.
Stanford has exceptionally difficult academic criteria for admission and ranks in the 99th percentile nationally for academic difficulty based on SAT and ACT scores of admitted freshmen. The school primarily accepts students with A averages in high school. In 2015, 5% percent of students that applied were accepted.