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.
The average GPA at Stanford is 4.18. This makes Stanford Extremely Competitive for GPAs. (Most schools use a weighted GPA out of 4.0, though some report an unweighted GPA. With a GPA of 4.18, Stanford requires you to be at the top of your class.