OUR SOLAR FAMILY 



11 



about the sun are larger than the earth, and two are nearer 

 to the sun than the earth. (Figure 2.) The planets in the 

 order of their distances from the sun are Mercury, Venus, 

 Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. In 

 the space between Mars and Jupiter there has been found 

 a group of small bodies which are called planetoids or 

 asteroids. The brightest of these is Vesta, which has a 

 diameter of not more 

 than 250 miles. 



"Shooting-stars " 

 (meteors) are small solid 

 bodies flying rapidly 

 through space. Some- 

 times they enter our at- 

 mosphere and become 

 heated by friction while 

 passing through it. Be- 

 cause they are thus 

 heated they give off light. 

 Sometimes they fall to 



thp parth as m pf write* Showing roughly the positions of the 



various planets and their moons. 



but more frequently they 



simply pass through the upper part of the atmosphere. 



They are in no sense true stars. 



Size and nearness to the sun are not the only respects 

 in which the planets differ from each other. The surfaces 

 of the planets Jupiter and Saturn, for example, are not solid 

 like the surface of the earth. Saturn has ten moons to the 

 earth's one. Venus and Mercury have none. The planet 

 Mercury, nearest neighbor to .the sun, must receive a with- 

 ering heat; while the temperature of Neptune, the most 

 distant planet, is probably colder than we can imagine. 



FIGURE 2. DIAGRAM OF THE SOLAR 

 SYSTEM 



