ZONE OF PLANETS BETWEEN MARS AND JUPITER. 55 



I assigned to them their respective periods. In this way 

 I thought that I might in some degree equalize their 

 ratios, which ratios regularly diminished toward the sun, 

 and enlarged toward the fixed stars." 



But Kepler himself soon rejected this idea as improb- 

 able, and it does not appear to have received any favor 

 from the astronomers of that time. 



An astronomer of Florence, by the name of Sizzi, 

 maintained, that as there were only seven apertures in 

 the head two eyes, two ears, two nostrils, and one 

 mouth and as there were only seven metals and seven 

 days in the week, so there could be only seven planets. 

 These seven planets, according to the ancient system of 

 astronomy, were Saturn, Jupiter, Mars, the Sun, Venus, 

 Mercury, and the Moon. 



In 1772, Bode published a treatise on Astronomy, in 

 which he first announced the singular relation between 

 the mean distances of the planets from the sun, which 

 has since been distinguished by his name. This famous 

 law may be thus stated. If we set down the number four 

 several times in a row, and to the second 4 add 3, to 

 the third 4 add twice 3 or 6, to the next 4 add twice 6 

 or 12, and so on, as in the following table, the resulting 

 numbers will represent nearly the relative distances of the 

 planets from the sun : 



