Compléter The Solar SystemVersion en ligne The Solar System par David Sánchez Bastia 1 The System is made up of the and all of the smaller objects that move around it . Apart from the Sun , the largest members of the System are the major . Nearest the Sun are four fairly small , rocky - Mercury , Venus , Earth and Mars . Beyond Mars is the asteroid ? a region populated by millions of objects . These are left - overs from the formation of the , 4 . 5 billion years ago . On the far side of the asteroid belt are the four gas - Jupiter , Saturn , Uranus and Neptune . These planets are much than , but very lightweight for their size . They are mostly made of and helium . Until , the furthest known planet was an world called Pluto . However , Pluto is dwarfed by Earth ? s Moon and many astronomers think it is too to be called a true . An object named Eris , which is at least as big as Pluto , was discovered very far from the Sun in 2005 . More than 1 , 000 icy such as Eris have been beyond Pluto in recent years . These are called Belt Objects . In 2006 , the International Astronomical decided that Pluto and Eris must be classed as " dwarf planets " . Even further out are the of the Oort Cloud . These are so far away that they are invisible in even the largest . Every so often one of these comets is disturbed and heads towards the Sun . It then becomes in the night .