The universe contains galaxies and vast spaces between them. It is made up of stars and planetary systems, including the 8 official planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. The inner planets are rocky while the outer planets are gaseous. There are also dwarf planets like Pluto, and small solar system bodies like asteroids that orbit in the asteroid belt between Mars and Jupiter, and comets with elliptical orbits. Constellations are patterns of stars, with 88 official ones, that appear differently in each hemisphere and change positions with the seasons.