SPACE TRAVEL GUIDES by Giles Sparrow THE OUTER PLANETS
4 The inner solar system is home to relatively small rocky planets Mercury Venus Earth and Mars and is surrounded by the asteroid belt a ring of small rocky objects The inner solar system is tiny compared to the vast expanse of the outer solar system and the rocky planets are also tiny compared to their outer neighbors We’ll be visiting the giant outer worlds Jupiter Saturn Uranus and Neptune each of which is dominated by gas and ice rather than rock The Sun is an enormous ball of exploding gas much larger than any planet Like all heavy objects it produces a pull called gravity This pull stops fast-moving objects from flying off into space and instead traps them in circular or oval paths called orbits INNER AND OUTER SOLAR SYSTEM SOLAR SYSTEM CENTER Get ready to blast off on the trip of a lifetime We’re going exploring into cold dark and dangerous territory to the outer reaches of the solar system The solar system consists of our nearest star the Sun and everything that circles around it The Outer Solar System URANUS 19 2 AU FROM SUN NEPTUNE 30 1 AU FROM SUN SATURN 9 5 AU FROM SUN JUPITER 5 2 AU FROM SUN
5 NEED TO KNOW Each giant planet has its own large family of moons in orbit around it and we’ll also be visiting many of these as we go We will then finish our trip with a visit to the comets and dwarf planets small icy astronomical bodies that hang at the very edge of our solar system Along the way we’ll learn about the unique histories features and hazards of these fascinating objects It’s going to be a fun trip but be careful it could also be a dangerous one MOONS AND OTHER BODIES It’s a long trip to the outer solar system The Earth is 93 million miles 150 million km from the Sun this is one astronomical unit or AU but the outer planets are much farther away The distances from the Sun are as follows Jupiter 5 2 AU Saturn 9 5 AU Uranus 19 2 AU Neptune 30 1 AU The dwarf planet Pluto see page 28 is 39 5 AU and the farthest point of the collection of icy objects known as the Kuiper belt see page 29 is about 47 AU MARS 1 5 AU FROM SUN EARTH 1 AU FROM SUN MERCURY 0 4 AU FROM SUN VENUS 0 7 AU FROM SUN ASTEROID BELT 2 8 AU FROM SUN EARTH’S MOON 238,855 MILES 384,400 KM FROM EARTH
