Both Mercury and the moon have surfaces, or crusts, COMPOSED almost entirely of rock and pocked with craters. Unlike Earth, which has an element-rich atmosphere in which incoming meteorites often burn, Mercury and the moon have thin atmospheres, called exospheres, that hold little gas and offer little insulation.Pythagoras THEOREM states that “In a RIGHT-angled triangle, the square of the hypotenuse side is equal to the sum of squares of the other two sides“. ... The sides of a right triangle (say a, b and c) which have positive integer values, when squared, are put into an EQUATION, also called a Pythagorean TRIPLE.Both Mercury and the moon have surfaces, or crusts, composed almost entirely of rock and pocked with craters. Unlike Earth, which has an element-rich atmosphere in which incoming meteorites often burn, Mercury and the moon have thin atmospheres, called exospheres, that hold little gas and offer little insulation.Pythagoras theorem states that “In a right-angled triangle, the square of the hypotenuse side is equal to the sum of squares of the other two sides“. ... The sides of a right triangle (say a, b and c) which have positive integer values, when squared, are put into an equation, also called a Pythagorean triple.