SPACE TRAVEL GUIDES by Giles Sparrow EARTH AND THE INNER PLANETS
4 The objects that orbit the Sun fall into two regions the inner and outer solar systems The inner solar system is a warm area close to the Sun and it contains four small planets that are mostly made of rock Mercury Venus Earth and Mars There are various other smaller worlds Earth’s Moon and the tiny satellites moons of Mars plus the asteroids most of which lie in a belt beyond Mars The outer solar system in contrast is cold and dominated by gas and ice rather than rock It contains four giant planets Jupiter Saturn Uranus and Neptune They are spread over a much wider area and surrounded by a variety of smaller moons and comets The Sun right is a huge ball of exploding gas much larger than any planet Like all heavy objects it produces a pull called gravity This stops fast-moving objects from flying off into space and instead traps them in circular or oval paths called orbits THE SOLAR SYSTEM BALL OF FIRE Get ready to blast off on the trip of a lifetime We’re off on a mission to explore the worlds of the inner solar system Mercury Venus and Mars as well as our own planet Earth and its Moon The solar system consists of our nearest star the Sun and everything that circles around it The Local Neighborhood
5 NEED TO KNOW Our tour of the solar system will start with Mercury the planet closest to the Sun From there we will travel away from the Sun visiting Venus Earth and the Moon before moving on to Mars and the asteroid belt Each of the astronomical bodies we’ll visit is a world in its own right with its own days seasons and years its own unique features and its own hazards It’s going to be a fun trip but it could also be a dangerous one TOUR OF THE PLANETS You’ll need strong sun block for your trip to Mercury and Venus and warm clothes for visiting chilly Mars Earth is 93 million miles 150 million km from the Sun this is one astronomical unit or AU Mercury and Venus are closer to the Sun than the Earth but Mars is farther away When measured in astronomical units the distances from the Sun are as follows Mercury 0 4 AU Venus 0 7 AU Mars 1 5 AU asteroid belt 2 8 AU MARS 1 5 AU FROM SUN EARTH’S MOON 238,855 MILES 384,400 KM FROM EARTH EARTH 1 AU FROM SUN MERCURY 0 4 AU FROM SUN VENUS 0 7 AU FROM SUN ASTEROID BELT 2 8 AU FROM SUN
