Size, Scale, Properties
	Planetary object, Stars: -Objects in the sky have properties (color, texture, features, brightness) that can be observed and described (K-4) -Sun and Moon appear to be the largest objects in the sky because they are nearby (K-4) -Relative sizes of the Sun and planetary objects including small bodies (comets, asteroids, moons) can be calculated and modeled (5-8) -Relative distances of the Sun of planetary objects including small bodies (comets, asteroids, moons) can be calculated and modeled (5-8) -The size of the orbits of all solar objects can be calculated and modeled (5-8) -Objects in the solar system differ in composition including rocky and gaseous materials (5-8) -The Sun is an average star (5-8) -Gravity is the force the keeps the objects of the solar system in orbits (5-8) -Each object in the solar system has an essentially fixed amount of each stable chemical atom or element (9-12) -Many objects in the solar system are in dynamic change (9-12) -The "big bang" theory places the origin of the universe between 10 and 20 billion years ago. (9-12) -Galaxies contain billions of stars. The universe contains billions of galaxies (9-12)