Planets in the solar system differ in terms of their relative location, number of moons, size, distance from the sun, composition, and ability to sustain life. Every object exerts gravitational force on every other object depending on the mass of the objects and the distance between them. The sun s gravitational pull holds Earth and other planets in their orbits. Earth s gravitational force holds the moon in orbit. The sun is one of billions of stars in the Milky Way galaxy that is one of billions of galaxies in the universe.
Scientists use a variety of tools to investigate the nature of stars, galaxies, and the universe.
Historically cultures have observed objects in the sky and related to them in various ways. Describe and compare the components of the solar system. Identify the nine planets in our solar system by name in order of location from the sun. Describe the characteristics of comets, asteroids, and meteors. Research and report on man made satellites orbiting various planets.