... planets 39 Stars, galaxies, and constellations 20 Our nearest star 30 Naming the planets 40 Planets and smaller space bodies 21 Gravity in space 31 Asteroids, comets, and meteors 41 The Sun and ... planets 39 Stars, galaxies, and constellations 20 Our nearest star 30 Naming the planets 40 Planets and smaller space bodies 21 Gravity in space 31 Asteroids, comets, and meteors 41 The Sun and ... dust and gas line from pole to pole) • The four planets nearest the Sun— Mercury, Venus, Earth, and Mars— are known as the inner planets • The other four planets Jupiter, Saturn, Uranus, and Neptune—...