182 
HAROLD’S DISCUSSIONS. 
The planets all revolve about the sun in elliptical 
orbits. The time required for one revolution varies 
as their distance from the central body. The earth 
requires one year—365 days, 5 hours, 48 minutes, 
48 seconds. Mercury 
requires only 88 of 
our days, and J^ep- 
tune about 164|^ of 
our years, to make a 
revolution. 
The ecliptic is the 
plane that passes 
through the center of 
the sun and of the 
earth as it moves in 
its orbit. 
Between Mars and 
Jupiter four small mi¬ 
nor planets have been 
discovered. Their or¬ 
bits are more eccentric 
and vary more from 
the plane of the eclip¬ 
tic than do those of 
the major planets. It 
would seem that they 
are the fragments of 
a larger planet which 
formerly revolved 
about the sun between 
Mars and Jupiter. 
